Minutes of the 94th Meeting of Protection Coordination Sub-Committee (PCSC – 94) of SRPC held on 29th January 2021
1. Introduction ...... 1 2. Confirmation of Minutes of last PCSC meeting...... 2 3. Grid Occurrences...... 2 3.1 Grid Disturbances (GD) ...... 2 3.2 Compliance of Regulations 5.2 (r) of IEGC ...... 3 4. Compliance by Constituents (Submitting status/ remedial measures/ certificate) ...... 3 5. Protection Management system (PMS) project ...... 6 6. Frequent tripping of 230 kV KKNPP-TTPS (ADL31) line ...... 7 7. Frequent faults in Talcher-Kolar HVDC line ...... 8 8. Other Protection Issues, if any, with the permission of the Chair ...... 9 9. Sending Agenda items for the PCSC meetings ...... 13 10. Date of next PCSC meeting ...... 13
Minutes of 94th Meeting of PCSC held on 29th January, 2021 Southern Regional Power Committee Bengaluru
Minutes of the 94th Meeting of Protection Coordination Sub-Committee (PCSC – 94) of SRPC held on 29th January 2021
1. Introduction
The 94th meeting of Protection Coordination Sub-Committee (PCSC-94) of SRPC was held in online mode through Webex on 29th January 2021. The list of participants is at Annexure-A.
Shri A. Balan, Member Secretary & Chairperson of Protection Sub-Committee, SRPC welcomed Members and Participants to the meeting, and briefed them on the following:
Apprised the forum regarding islanding meeting convened by Min. of Power (MoP), Govt. of India. MoP desired to have islanding scheme for all major cities. In SR region, islanding scheme has to be formulated for Bangalore city as well. Informed that PMS project is nearing completion and requested all members to actively participate in PMS meetings to resolve deficiencies, if any, so that the software could be utilized effectively. Pointed out that majority of the trippings listed out in agenda for discussion are due to Busbar protection operation. He emphasized on the necessity of effective substation maintenance to be practiced and requested utilities to religiously take up necessary preventive measures to avoid occurrence of similar faults. Member secretary also requested constituents to analyse the tripping incidences thoroughly and to present respective Grid Disturbance cases from the forthcoming PCSC meeting.
Executive Director, SRLDC, expressed concern regarding the load loss occurring due to trippings in SR region and urged SR constituents to make efforts to minimize trippings. He also pointed out that majority of GDs to be discussed in the meeting occurred at 220kV level and urged state utilities to address the issues at lower voltage level, and maintain proper grid discipline. He also raised the issue of improper submission of data and details of tripping by utilities as per IEGC and requested the attention of all concerned in this regard. He also lauded the steps taken by the Monitoring Committee of PMS project focusing expeditious Go-Live of the project.
Superintending Engineer (Protection) and Convener of Protection Committee of SRPC took up the agenda for deliberation. He informed the forum that the apparently large agenda was due to covering of all tripping events involving non-operated/ mal-operated protection systems that occurred in October – December 2020. He also highlighted that tripping reports furnished by constituents in Tripping portal of SRLDC were mostly incomplete with majority of fields being left blank or ‘NIL’ entry, and urged all SR-Constituents to furnish full details.
In this connection, SRLDC was also requested to provide latest PSSE Basecase including the elements to be commissioned in the coming two months so that comprehensive exercize of reviewing OVR grading of 400 kV & 765 kV lines of SR can be undertaken.
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2. Confirmation of Minutes of last PCSC meeting
The minutes of the 93rd meeting of PCSC were circulated vide No: SRPC/SE-III/PCSC- 93/2020/ 50-87 dated 18th January 2021. No comments were received from the utilities. Minutes of PCSC-93 were confirmed.
3. Grid Occurrences
3.1 Grid Disturbances (GD) Agenda: Grid Disturbances (GD) and Grid Incidences (GI) occurred during the period October - December, 2020, given at Annexure-I, would be discussed in the meeting.
a) Constituents are requested to furnish the following information in respect of the above grid occurrences to have fruitful discussions: (i) Detailed analysis of the events (ii) SLD or equivalent pictorial representation clearly showing: a. Location of fault with distance b. Fault details with type &relay indications c. CT/PT/CVT rating details with location d. Bus-bar arrangement/ Configuration of feeders e. CB positions (OPEN/ CLOSE) at the time of fault f. Isolator & Earth-switch positions (OPEN/CLOSE) g. Voltage, frequency & power flows with direction at the time of fault (iii) Output of Event logger & Disturbance recorder (iv) Remedial Action(s) taken (v) Relay setting details
b) Constituents are requested to furnish full particulars of the tripping events pertaining to their system, preferably in the form of power point presentation, well in advance (latest by 26-01-2021) to the scheduled meeting date, to take up for discussion in the meeting.
c) Constituents are requested to present the fault analysis with clear diagrams and remedial actions taken for the trip events, in the meeting.
Deliberations: 3.1.1 The trippings due to GDs, GIs, A/R failure/ non-operation, and PLCC mal- operation that had occurred during October - December, 2020 were discussed in the Meeting. The deliberations and recommendations of the PCSC forum are at Annexure–B for needful action. The details of the tripping events including relevant PMU plots presented by SRLDC in the meeting are at Annexure-F for kind reference. 3.1.2 The matter of timely uploading of tripping files, which helps in analyzing the events for corrective actions/solutions required was once again brought to the notice of all Constituents. The need to upload the files within the time frame stipulated in the IEGC was reiterated.
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3.2 Compliance of Regulations 5.2 (r) of IEGC Agenda: In compliance of Regulations 5.2 (r) of IEGC, which is given below: “5.2 System Security Aspects (r) All the Users, STU/SLDC and CTU shall send information/data including disturbance recorder/sequential event recorder output to RLDC within [24 hours]20 for purpose of analysis of any grid disturbance/event. No User, SLDC/STU or CTU shall block any data/information required by the RLDC and RPC for maintaining reliability and security of the grid and for analysis of an event.”
a) Constituents are required to furnish the following information in respect of Grid Occurrences(GD/GI) within 24 hours of occurrence of the same to SRLDC/ SRPC: i. First Information Report (FIR) ii. Event Logger (EL) output iii. Disturbance Recorder (DR) output iv. Trip event analysis report-TR (with pre and post fault system conditions)
b) Non-furnishing of tripping details (FIR/DR/EL/TR) for the period 16.10.2020 – 31.12.2020 had been brought to Constituents’ notice vide the following SRPC letters: (i) No. SRPC/ SE-III/ PCSC/ 2020/ 3035-54 dated 13.11.2020, (ii) No. SRPC/ SE-III/ PCSC/ 2020/ 3067-80 dated 23.11.2020, (iii) No. SRPC/ SE-III/ PCSC/ 2020/ 3154- 171 dated 09.12.2020, (iv) No. SRPC/ SE-III/ PCSC/ 2020/ dated 01.01.2020
c) Non-compliance in this regard would be discussed in the meeting.
Deliberations: 3.2.1 Non-furnishing of tripping details (FIR/DR/EL/TR) for the 16.10.2020 – 31.12.2020 had been brought to Constituents’ notice vide letters:
(i) No. SRPC/ SE-III/ PCSC/ 2020/ 3035-54 dated 13.11.2020, (ii) No. SRPC/ SE-III/ PCSC/ 2020/ 3067-80 dated 23.11.2020, (iii) No. SRPC/ SE-III/ PCSC/ 2020/ 3154- 171 dated 09.12.2020, (iv) No. SRPC/ SE-III/ PCSC/ 2020/ dated 01.01.2020
Constituents were requested to upload all tripping files in timely manner as mandated by IEGC.
4. Compliance by Constituents (Submitting status/ remedial measures/ certificate) 4.1. Status of implementation of Recommendations of Protection Coordination Sub-Committee (PCSC)-93 Agenda: Status of implementation of recommendations of PCSC-93 shall be presented by constituents in the forthcoming PCSC.
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Deliberations:
4.1.1. The status of implementations of recommendations of PCSC-93 was discussed in the meeting. KPCL, TANTRANSCO, NPCIL(MAPS), PGCIL(SR-1) and KPTCL had furnished the updated status of recommendations. All other constituents were requested to furnish the updates at the earliest.
4.1.2. Updated status on the implementation of PCSC recommendations on regular basis, was requested form all concerned.
4.2. Status of implementation of Recommendations Protection Coordination Sub-Committee (PCSC), which are pending Agenda: a) The status of implementation of PCSC recommendations (up to 93rd PCSC meeting), which are pending, is at Annexure-II.
b) The latest status on the same may please be sent latest by 26.01.2021, to place the same before the sub-committee.
Deliberations:
4.2.1 The status of implementation of pending PCSC recommendations was discussed in the meeting. The updated status of the same as on 02.03.2021 is at Annexure–C.
4.2.2 The Constituents were requested to comply with the recommendations, which were pending, and requested to submit the status of compliance latest by 12.03.2021.
4.3. Remedial measures for "Transmission Elements under Forced Outage"
Agenda: a) The Constituents are requested to furnish the remedial measures/ actions taken by them for the tripping events, as circulated vide this office emails (Annexure-III), to discuss the same. b) The tripping events are based on the daily reports at SRLDC website https://www.srldc.in/DailyReport.aspx under the menu: Reports->Daily-> "TL under Forced Outage". Deliberations:
4.3.1 The tripping incidents of the transmission elements under forced outages, for which the constituents have to furnish remedial measures taken, were circulated vide mail dated 26.02.2021 (Annexure-D). The Constituents were requested to take appropriate action and to furnish specific remedial measures/ action taken covering one or the other items from the following indicative list in time, so as to forward the same to Central Electricity Authority:
Brief details of line patrolling carried out (with tower location). Brief details of RoW maintenance (by proper Tree-cutting) resorted to. De-capped insulators replacement. DC earth fault removal. PLCC cards replacement. Relay settings modification.
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Steps taken to put A/R or CB into service after they have been locked- out. Faulty equipment replacement. Reference to OEM in case of equipment failure. Brief Details of tests carried out to ascertain the healthiness of various equipment (Power Transformer/ Reactors/ Surge Arrestors/ Circuit Breakers/ CTs/ PTs/CVTs), like Insulation Resistance (IR) test, Winding Resistance test, Capacitance test, Tan delta test, DGA test, Leakage current test, CRM/ DCRM test, etc. Any other appropriate remedial measure.
4.3.2 Need of appropriate timely action was emphasized and requested all concerned to report remedial measures/ actions taken regularly, possibly on weekly basis, so that the remedial measures taken would be compiled and reported to the appropriate authorities.
4.4. Certificate for Healthiness of Batteries
Agenda: a) As per the MoP direction, given in pursuant to recommendations of the Enquiry Committee (NEW grid disturbance on 30th& 31st July, 2012), the monthly certificate for healthiness of batteries, installed at 220 KV and above voltage level Substations (for power supply to Relays, RTUs and PLCC equipment) are required to be obtained by RPCs, from their respective Constituents and furnish the same to CEA/ MoP. b) With reference to above, the Constituents have been requested to submit the certificate on healthiness of batteries on monthly basis (i.e. status for a month shall be sent by the 7th day of the following month) to SRPC Secretariat. c) The sought status for the month of October - December, 2020 is awaited from the following SR-Constituents: Month Utility Name October 2020 TPCIL November 2020 TPCIL December 2020 APGENCO (Hydel), KPCL, KPTCL, KSEBL, NTPC (Simhadri), TPCIL
The non-reporting of status of healthiness of batteries may be discussed. Deliberations: 4.4.1. The Constituents were requested to submit the certificate on healthiness of batteries on monthly basis (i.e. status for a month shall be sent by the 7th day of the following month) to SRPC as per the format given below:
S Station Application Battery Battery Charger Remarks No Station Code Type Protection/ Details Status Details Status Brief Details of unhealthy Name (Healthy/ (Healthy/ battery banks and/ or DC (PS/ SS) Communication Unhealthy) Unhealthy) leakage along with proposed time-lines for rectifying the same shall be mentioned. 1 Station- Protection (Bank- A 1)
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Protection (Bank- 2) Communication (Bank-1) Communication (Bank-2) 2 Station- … B … … …
Note: 1. Code is the short name of the Station 2. PS – Power Station; SS – Substation
4.4.2. The sought status for the month of October - December, 2020 was not received from following constituents:
Month Utility Name October 2020 TPCIL November 2020 TPCIL December 2020 NTPC (Simhadri), TPCIL
The above constituents were requested to furnish Battery Healthiness report for respective months.
5. Protection Management system (PMS) project
Agenda:
a) Even though PMS project as a whole is yet to be operationalized, Protection Database Management System (PDMS) of PMS project, which hosts relay settings data of SR-Constituents, has been put into on-line mode so that Constituents can cross-check the relay settings pertaining to their system, and get them corrected by appropriately taking up with the Project Implementation Agency (PIA). Similarly, Data Management Network System (DMNS), which acts as a medium to communicate changes in Protection Elements and Network Elements that take place in one’s system to PIA, has also been put into on-line mode so that Protection Database of PMS project is always kept up-to-date. In this regard, Constituents are requested to (i) complete verification of relay settings pertaining to their respective system uploaded in PDMS by the end of January, 2021, and (ii) regularly inform PIA regarding network modification and relay setting changes through DMNS in order to ensure that Protection Database of SR being modeled in PMS is kept up to date.
b) The latest PSCT database and Station SLDs were uploaded in ftp link and was communicated vide SRPC mail dated 18.01.2021. All Constituents were requested to download them and verify the features of PSCT software. All license holders (the Utility personnel responsible for carrying out various studies and to whom PSCT dongles had been given) were requested to focus on utilizing the PSCT software and to furnish deficiencies noticed, if any, or suggestions for improvements.
c) All SAT features of PMS project are close to being completed and efforts are being made to operationalize (commencement of Go-Live) of the PMS project in
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February – March, 2021.
The status regarding PMS project would be discussed in the meeting.
Deliberations: 5.1. SRPC apprised the forum that PDMS had been made online since January 2020 and requested strong and expeditious action from all utilities in verifying the relay settings and intimating discrepancies to PRDC. It was also informed that TSTRANSCO vide mail dated 25.01.2021 highlighting the discrepancies observed in relay settings, had been forwarded to Project Implementing Agency (PIA) for appropriate action. 5.2. SRPC stated that regular review meetings were being conducted with the PIA to verify and assess the status of PMS project and to ascertain the progress made by PIA in completing the pending SAT features/ observations with regard to PMS software. The last such review meeting was conducted with PRDC on 22.01.2021. 5.3. All license holders (the Utility personnel responsible for carrying out various studies and to whom PSCT dongles had been given) were requested to take steps to familiarize themselves with the PMS software. 5.4. All constituents were also strongly urged to furnish the data relating to Network changes through DMNS without fail, in order to ensure that Protection Database of SR being modeled in PMS is kept up to date and to ensure that the studies conducted in PSCT, which gets its database imported from PDMS, are meaningful. 5.5. SRPC also apprised that efforts were being made to operationalize (commencement of Go-Live) the PMS project by March, 2021.
6. Frequent tripping of 230 kV KKNPP-TTPS (ADL31) line
Agenda:
a) The frequent tripping issue of 230KV KKNPP-Tuticorin line (ADL31) was discussed in 87th and 92nd PCSC meeting of SRPC. In subsequent SRPC¬PCSC meeting, TANTRANSCO had informed that all measures had been taken from their end to address the issue. Purchase order was placed for bird guards and insulator replacement.
b) It was also informed by TANTRANSCO that insulator has been replaced in 50 % length of line and the remaining would also be replaced by March 2021. Similarly, bird guards and colored flags would also be placed in the affected areas.
c) However, NPCIL(KKNPP), vide letter dated 10.12.2020 informed, that during December 2020 there have been 5 trippings in a span of just 6 days. The list of trippings since October 2020 is attached at Annexure-IV.
The issue of frequent tripping of the line would be discussed in meeting.
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Deliberations: 6.1.1. NPCIL (KKNPP) stated that the line had been tripping frequently, over a long period of time. In the month of December, 2020 itself there have been 6 instances of tripping. 6.1.2. SRPC informed the forum that TANTRANSCO, vide email dated 20.01.2021 (attached at Annexure-E), had requested Member secretary, SRPC and ED, SRLDC to give instructions to Station Director Kudankulam to hand-trip both HV/ LV of both 400/230kV ICTs at their end and keep it open until restoration of 400kV KKNPP – Tirunelveli line-1. TANTRANSCO had quoted this based on a remark specific to Kakrapara APP mentioned in MoM of 17th and 18th standing committee on Power System Planning in SR region held in 2003 & 2004 respectively. 6.1.3. SRPC pointed out that the context & background of the remark quoted from the MoM of the 17th and 18th standing committee, wherein suggestion to keep open 400/ 220kV ICTs at KAPP to avoid power rushing to 220kV sides and overloading of 220kV lines, was not known and may not be valid under present conditions. Moreover, the Kakrapara APP, for which the above said remark had been given is not SR; hence, suggestion/ recommendation given for KAPP which is not in SR cannot be generalised and made applicable for Kudankulam NPP in SR. It was also suggested that operational issues in respect of lines/ ICT’s may be taken up in appropriate forum of SRPC, instead of in PCSC. 6.1.4. SRPC also requested TANTRANSCO to ensure proper ROW for the line, and to expedite the process of insulator replacement, placing of bird guards, coloured flags etc. as suggested in PCSC-87 and PCSC-92.
7. Frequent faults in Talcher-Kolar HVDC line
Agenda:
a) NTPC-Talcher, vide email dated 28.12.2020 (attached at Annexure-V), had informed that generating units at Talcher trip frequently due to blocking of Talcher-Kolar HVDC poles. They pointed out that since the implementation of SPS scheme, NTPC-Talcher Kaniha stage-II experienced numerous unit trippings and backing down on account of SPS operation of Talcher-Kolar HVDC line fault, for reasons not attributable to the station.
The issue would be discussed in meeting.
Deliberations:
7.1. The issue was deliberated in the meeting. SRPC stated that the tripping mentioned by NTPC were mainly due to problems at HVDC Talcher end. In this regard, PGCIL-SR1 was requested to ensure proper ROW along the length of the line, and take up the matter suitably with HVDC Talcher.
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8. Other Protection Issues, if any, with the permission of the Chair For Information of the PCSC
8.1 Instances of SPS Operation SRLDC, furnished the following SPS operations, which took place in SR during October – December 2020:
Actual Load Relief obtained, MW
S. Time
Date Reason
No (hr.) TS KL
KA AP
TN
PED SPS for Talcher – Kolar HVDC Bipole: Pole 1 tripped due to line fault protection at Talcher after recovery attempt. ESOF was received at Kolar end. Pole-2 went to metallic return mode 1 04-Oct-2020 11:53 immediately and then ground 368 230 - 290 168 - return mode with power flow of 144MW at Kolar end due to electrode current limitation. Antecedent Power flow was 1280MW. SPS trip signal-1 & 2 operated since power loss was 1000MW. SPS for Talcher – Kolar HVDC Bipole: Pole-1 tripped due to receipt of EOf signal from Talcher end. Line fault recovery sequence had operated. Antecedent flow at talcher was 1650MW at 2 23-Oct-2020 21:34 285 260 - 0 - - Talcher and 1542MW at Kolar end. After tripping of Pole-1, Pole-2 went to metallic return mode with a power flow of 842MW at Kolar end. SPS trip signal-1 operated since power loss was more than 500MW. SPS for 765 kV Sholapur- Raichur D/C: SPS operated at Raichur S/S and the line flow of 765kV Raichur- Sholapur D/C Line at the time of 20-Nov- SPS operation was 2880MW (as 3 19:15 249 - - - - - 2020 per SCADA). No load loss reported by Karnataka, Kerala and Telangana. SPS trip signal RS-2 operated.
4 20-Nov- 19:20 SPS for 765 kV Sholapur- 143 - 25 - - -
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2020 Raichur D/C: SPS operated at Raichur S/s and the line flow of 765kV Raichur- Sholapur D/C Line at the time of SPS operation was 2910MW (as per SCADA). No load loss reported by Karnataka. SPS Trip Signal RS-3 Operated. SPS for Talcher – Kolar HVDC Bipole: HVDC Talcher Kolar Pole-1 tripped at 16:33 hrs due to operation of line fault protection at Talcher end after fault recovery attempt. ESOF was received at Kolar end. Pole- 5 15-Dec-2020 16:33 2 went into ground return mode 373 295 - 250 215 - with 150 MW. Antecedent flow on Pole-1&2 was 1500 MW at Talcher end and 1400 MW at Kolar end. SPS trip Signal-1 and 2 operated since the power loss was more than 1000 MW. SPS Trip Signal TK-1 & TK-2 operated. SPS for Talcher – Kolar HVDC Bipole: HVDC Talcher Kolar Pole-1 tripped at 21:25hrs due to operation of ESOF at Kolar end. After the tripping of Pole-1, power flow in Pole-2 was 1140MW. Later Pole-2 went into 6 20-Dec-2020 21:25 242 233 - 160 - - ground return mode with 150 MW. Antecedent flow on Pole- 1&2 was 1650 MW at Talcher end. SPS trip Signal-1 operated since the power loss was more than 500 MW immediately afer the tripping of Pole-1. SPS Trip Signal TK-1 operated. SPS for 765 kV Sholapur- Raichur D/C: SPS operated at Raichur S/s and the line flow of 765kV Raichur- Sholapur D/C Line at the time of 7 10-Dec-20 18:34 276 - 83 - 117 - SPS operation was 2900MW as per PMU data at 765kV Sholapur SS (Flow towards Raichur). No load loss reported by Karnataka. SPS trip signal RS-2 operated. 8 21-Dec-20 6:39 SPS for 765 kV Sholapur- 201 - - - 81 -
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Raichur D/C: SPS operated at Raichur S/s and the line flow of 765kV Raichur- Sholapur D/C Line at the time of SPS operation was 2900MW as per PMU data at 765kV Sholapur SS (Flow towards Raichur). No load loss reported by Karnataka and Telangana. SPS trip signal RS-2 operated. SPS at Kudankulam Nuclear Power Station Unit#1: As per the information received, U#1 at KKNPP got tripped at 11:05hrs on 14-12-2020 due to tripping of feed water pump and there was no SPS operation during this event even though 9 14-Dec-20 11:05 ------generation at KKNPP U#1 was around 1000MW during antecedent conditions. From 400kV line flows PMU plot, it was observed that the ramp down had taken around 1.24s. Tripping of KKNPP U#1 and nonoperation of KK-1 signal. SPS at Kudankulam Nuclear Power Station Unit#2: As per the information received, U#2 at KKNPP got tripped at 12:38hrs on 09-12-2020 due to steam valve leakage and there was no SPS operation during this event even though generation at 10 9-Dec-20 12:38 ------KKNPP U#2 was around 1000MW during antecedent conditions. From 400kV line flows PMU plot, it was observed that the ramp down had taken around 1.2s. Tripping of KKNPP U#2 and nonoperation of KK-2 signal. SPS at Kudankulam Nuclear Power Station Unit#2: As per the information received, U#2 at KKNPP got hand tripped 11 29-Dec-20 08:38 ------at 08:48hrs on 29-12-2020 due to leak developed in condensate System. Hand Tripping of KKNPP U#2
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8.2 Network Configuration Changes The Network configuration changes reported during September – December 2020 are as follows: a) 220kV Manuguru – BTPS line 1 & 2 (46ckm) of TSTRANSCO was commissioned on 04.09.2020. b) 220kV Kamalapuram – V K Ramavaram line 1 & 2 (28.32ckm) of TSTRANSCO was commissioned on 04.09.2020. c) 220/ 11kV 50MVA Medigadda SS was commissioned by TSTRANSCO on 05.09.2020. d) LILO of 400kV QMDC line from Krishnapattanam – Chittoor to 400/ 220/ 132V Rachagunneri SS (126.6ckm) was commissioned by APTRANSCO on 15.09.2020. e) 400kV Krishnapattanam – Rachagunneri (100.49ckm) was commissioned by APTRANSCO on 15.09.2020. f) 400kV Rachagunneri – Chittoor (148.58ckm) was commissioned by APTRANSCO on 15.09.2020. g) 220kV Nandyala SS in Kurnool (2x50+1x31.5 MVA) was augmented to (3x50 +1x31.5 MVA) by APTRANSCO on 09.09.2020. h) 220kV RS Gooty in Anantapuram District (1x160+1x100 MVA) was augmented to (2x160 MVA) by APTRANSCO on 19.10.2020. i) TSTRANSCO – LILO of 220kV Mamdipally-Shadnagar to Proposed 220 KV SS Kothur CKT NO. 1, 220 KV, 0.790 CKM, was commissioned on 01.10.2020. j) LILO of 220 KV Shamshabad - Kethireddypalli to 220 KV SS Kothur ckt No.1, (18.680 ckm) was commissioned by TSTRANSCO on 01.10.2020. k) 220/132/33 kV 400 MVA Kothur SS, was commissioned by TSTRANSCO on 01.10.2020. l) 220/11kV, 100 MVA Medigadda Sub-Station was commissioned by TSTRANSCO on 05.10.2020. m) 220/11kV, 150 MVA Annaram Sub-Station was commissioned by TSTRANSCO on 09.10.2020. n) 220/11kV, 150 MVA Sundilla Sub-Station was commissioned by TSTRANSCO on 16.10.2020 (2 No. 50 MVA pump PTRs on 16.10.2020 & 1 No. 50 MVA Station PTR on 28.10.2020). o) 220kV DC line from 400/220/132kV SS Rachagunneru to the 220kV SS Naidupeta in SPSR Nellore District(VCIC), of 30.43 ckm, was commissioned by APTRANSCO on 30.11.2020. p) 315 MVA Transformer (2nd) was commissioned by APTRANSCO on 05.11.2020 at 400/220kV SS Podili. q) At 400/220/132 kV SS Rachaganneri, 315 MVA Transformer was commissioned by APTRANSCO on 30.11.2020. r) At 400/220 kV Hindupur S/S 80 MVAR Bus reactor was commissioned by APTRANSCO on 20.11.2020. s) At 400/220/132kV SS Rachaganneri, 125 MVAR Bus Reactor was commissioned by APTRANSCO on 30.11.2020. t) 220/11 kV SS Medigadda SS was commissioned on 04.11.2020 by TSTRANSCO with charged capacity of 150 MVA. u) 220/11 kV SS Annaram SS was commissioned on 23.11.2020 by TSTRANSCO with charged capacity of 50 MVA. v) 400/220/11 kV Sundilla SS was commissioned by TSTRANSCO on 28.11.2020 with charged capacity of 100 MVA. w) 400/220/132 kV SS Rachagunneri, 315 MVA was commissioned by APTRANSCO on 18.12.2020.
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x) 400/220KV SS Podili, 315 MVA was commissioned by APTRANSCO on 30.12.2020. y) 220kV SS Kamavarapukota in west Godavarai district (Existing MVA 2x100+1x60), was augmented to 1x100+2x160 MVA capacity by APTRANSCO on 07.12.2020. z) 400/220KV SS Podili, 80 MVAR Bus/Line reactors was commissioned by APTRANSCO on 30.12.2020.
9. Sending Agenda items for the PCSC meetings
All constituents were requested that Agenda Items for the PCSC meetings, if any, may be sent latest by 5th working day of the month to SRPC Secretariat to compile and circulate the same, so as to have fruitful discussions in the PCSC meetings.
10. Date of next PCSC meeting
The date of 95th meeting of PCSC will be decided in due course. *****
Minutes of 94th Meeting of PCSC held on 29th January, 2021 Page 13 of 13 Annexure-A
Southern Regional Power Committee 94th PCSC Meeting List of Participants Sl. No. Name (S/Shri) Designaton Organisation Phone Email 1 PASS Anjeneya Prasad SE/Power Systems APTRANSCO 8333886160 [email protected] 2 K Anantha Srinivas EE/System Protection APTRANSCO 8330990827 [email protected] 3 M Srinivas Rajesh DEE/System Protection APTRANSCO 7382296879 [email protected] 4 K Srikanth Reddy AEE/System Protection APTRANSCO 9494712371 [email protected] 5 Y S Ramaswamy TSS BHAVINI 9445022991 [email protected] 6 C Rajalakshmi SO/E, EMU BHAVINI 9445022938 [email protected] 7 S Bhaskar SO/E, TU BHAVINI 9445022940 [email protected] 8 Ganapathi gatta SO/E, TU BHAVINI 9445394614 [email protected] 9 Sudhakar YS Manager E&I JSW Energy Ltd 9449849723 [email protected] 10 R Suresh Kumar STE(E&I) KKNPP 9442202187 [email protected] 11 Pradeep M AE KPCL 9141607644 [email protected] 12 Channabasavaraju EE KPCL 9481547035 [email protected] 13 B V Girish SEE KPTCL 8277893665 [email protected] 14 Pushpa EE KPTCL 9480812570 [email protected] 15 Rajeshwari Bhat AEE KPTCL 9448365116 [email protected] 16 Abdul Gafoor.P.K EE KSEBL 9446008256 [email protected] 17 Pradeep Kumar.S EE KSEBL 9446008241 [email protected] 18 D.Venkata Ramana Rao SO/G NPCIL,MAPS 9445397502 [email protected] 19 D. Shanmugavadivel EE/Auto SS PED 9489080380 [email protected] 20 A. Selvaraj AEE/M/VASS PED 9489080381 [email protected] 21 K. Sudhakar Rao DGM POWERGRID-SR1 9490611112 [email protected] 22 A. Santhosh Kumar Chief Manager POWERGRID-SR1 8332995437 [email protected] 23 B.Sridhar Sr DGM POWERGRID-SR2, Kolar 9449596035 [email protected] 24 S.Subramanyam Chief Manager POWERGRID-SR-II 9148095075 [email protected] 25 M VENKATA RAO DEE SRBPH-APGENCO 9493174394 [email protected] 26 M SREEKANTH AEE SRBPH-APGENCO 9490130728 [email protected] 27 B Chinna Linganna AE SRBPH-APGENCO 8332850490 [email protected] 28 Abhimanyu Gartia ED SRLDC, POSOCO 29 S P Kumar CGM SRLDC, POSOCO 30 Jane Jose Senior GM SRLDC, POSOCO 31 Arthi Sahaya Rones V Manager SRLDC, POSOCO 9480811826 [email protected] 32 Vamshi Ballikonda Dy Manager SRLDC, POSOCO 33 Nikhitha ET SRLDC, POSOCO 34 B Chinna Linganna AEE/MRT-II SRNPH, APGENCO 8332850490 [email protected] 35 A. BALAN Member Secretary SRPC [email protected] 36 N R L K PRASAD Superintendenting Engineer SRPC [email protected] 37 LEN. J.B Executive Engineer SRPC 9449682204 [email protected] 38 BETSY SEBASTIAN Assistant Executive Engineer SRPC [email protected] 39 S.SUNIL KUMAR EXECUTIVE ENGINEER / EPC4/DESIGN P&C TANTRANSCO 9445442320 [email protected] 40 V.Umamageswaran Executive Engineer/P&C/Sriperumpudur TANTRANSCO 9445396745 Executive Engineer/Operation/Tuticorin Auto 41 Mr.Samuel TANTRANSCO 9443165462 230kV SS 42 P.Chandrasekeran Executive Engineer / P&C - 2 TANTRANSCO 9445892707 43 V.SHOBAN BABU ADE/VS/HQ TSGENCO 9493174385 [email protected] 44 D.Venkata Ramana Rao ADE/NSHES TSGENCO 9491049480 [email protected] 45 V. Ramakrishna AE/NSHES TSGENCO 8331044045 [email protected] 46 A.Ravi Shankar ADE/LJHES TSGENCO 9493174748 [email protected] 47 V.Bharath Kumar AE/LJHES TSGENCO 9490997558 [email protected] 48 I.Sandeep AE/MRT TSGENCO 9177123567 [email protected] 49 G.Praveen kumar ADE/System Protection TSTRANSCO 9491067449 [email protected] 50 V. Vamshi krishna reddy AE/System Protection TSTRANSCO 9491049376 [email protected]
Page 1 of 1 Annexure-B Grid Occurrences Analysis - 94
I. Details of Grid Disturbances: Sl. Details of Event Date &Time Reason Generati Load Loss Category No. on Loss (MW) (MW) Triggering incident was failure of R- phase CT connected to 220kV Sabaigiri - Edamon feeder-2. As Complete Outage 01-Oct-20 reported LBB operated and all 1 of 220kV Sabarigiri 220 16 GD-1 18:06 hrs connected elements tripped at GS of KSEB Sabarigiri end only resulting in complete outage of 220kV Sabarigiri station. SLD: The single line diagram of 220kV Sabarigiri GS as furnished by KSEBL is enclosed at the end.
Bus configuration and arrangement: Double Bus with Bus coupler (Main Bus and Transfer Bus)
Bus Elements connected Main Bus 220kV Sabarigi – Theni line , 220kV Sabarigiri – Pallom ,220kV Sabarigiri – Edamon line-2, 220/ 66kV 5OMVA Transformer, Unit #l and Unit#3 Transfer Bus 220kV Sabarigiri – Edamon line-1, 220kV Sabarigiri – Edamon line-3, 220kV Sabarigiri – Ambalamugal line, Unit #2 and Unit#5
Antecedent Conditions: 220kV Sabarigiri – Edamon line-3 was under shutdown. Generating unit – 4 & 6 was not in service.
Connectivity Diagram:
Tripping of 220kV Sabarigiri – Theni line-2: Sabarigiri (KSEBL) end: As per FIR/ DR/ EL/ TR, line tripped on R-E fault at 18:07.09.489 hrs. As per DR distance protection reverse zone picked up at 18:07:09.417 hrs. EL is incomplete
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Annexure-B Theni (TANTRANSCO) end: As per FIR/ TR, line was holding at Theni end
Complete Outage of 220kV Sabarigiri SS Sabrigiri (KSEBL) end: As per FIR/ DR/ EL/ TR, all elements at 220kV Sabarigiri SS tripped on R-E fault at 18:07 hrs. It was stated in FIR/TR that the R-E fault was due to flashing of R-ph CT of 220kV Sabarigiri – Edamon line-2. As per KSEBL report all elements connected to Main Bus at 220kV Sabrigiri SS tripped on R-E fault at 18:07:25.314 hrs. due to operation of BBP of Main Bus (Bus-1).
As per KSEBL report dated 06.11.2020:
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Annexure-B
Deliberations: The triggering incidence for the events was R-ph CT failure of 220kV Sabarigiri – Edamon line-2. At Sabarigiri end, BBP of Main Bus operated. At Sabarigiri end, reverse zone pickup and non-opening of R-pole CB also were observed. At Edamon end the fault was picked up in Zone-2 and tripped after Zone-2-time delay of 350msec. Operation of BBP of Main Bus resulted in tripping of all Main bus connected elements i.e., - 220kV Sabarigi – Theni line, 220kV Sabarigiri – Pallom line ,220kV Sabarigiri – Edamon line-2, 220/ 66kV 5OMVA Transformer, Unit #l, Unit#3 and Bus coupler. At Sabarigiri end of 220kV Sabarigiri – Edamon line-2, as the CT was on line side, in spite of opening of CB of 220kV Sabarigiri – Edamon line-2, the fault was continued to be fed from Edamon end. R-ph CT at Sabarigiri end continued to sense the fault current resulting in operation of LBB protection of 220kV Sabarigiri – Edamon line-2 CB after 250msec. But no DT sent signal to remote end was observed. It was noted that despite the opening of bus coupler, operator hand tripped all elements connected to transfer bus causing GD at 220kV Sabarigiri GS. KSEBL informed that at Sabarigiri, LBB operation was not configured for sending of DT and LBB timing was 250msec. LBB timing of 220kV Sabrigiri – Edamon line-2 was revised to 200msec and LBB was configured for sending of DT. They also informed that similar LBB reconfiguration for other feeders at 220kV Sabarigiri GS is in progress. SRLDC expressed concern regarding the location of fault. KSEBL had stated in their report dated
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Annexure-B 06.11.2020 that fault was between CT and CB of 220kV Sabarigiri – Edamon line-2. But SRLDC pointed out that if that was the case fault current should last till 350msec, since it would be fed from Edamon side. However, the fault current was observed only for 250msec, which indicates that fault current was contributed from Sabarigiri end till LBB operation. Since this happened in spite of BBP operation on 220 kV Bus-1, some non-isolated source from Sabarigiri could have possibly led to feeding of the fault till LBB operation. In this regard, KSEBL was requested to check the status of CB of 220/ 66kV 50 MVA Transformer (to ascertain its proper opening during BBP operation of Main bus) and also the location of fault. KSEBL shall examine DRs of Main-2 relay as well.
Remedial Measures taken by KSEBL: KSEBL informed that End-Zone protection was not configured in the numerical bus bar protection. The technical possibility for providing end zone protection would be explored. This would be carried out by 30-11-2020. Stage2 LBB period which was set at 250ms would be reduced to 200ms.This would be carried out by 30-11-2020. Instruction had been conveyed to the operator to avoid unnecessary switching off healthy bays unless it is dangerous to human beings. Faulty R phase CT of SBEM#2 feeder was replaced with a new one.
Recommendations: KSEBL to submit Equipment failure report for the failed CT to CEA with a copy to SRPC. KSEBL to revise LBB timings for all feeders at 220kV Sabarigiri GS to 200msec (existing 250msec) and configure LBB operation for sending of DT to remote end. End zone protection shall also be configured for all 220 kV lines at their 220 kV Sabarigiri GS.
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Annexure-B Triggering incident was R -E fault in 66kV Feeder no-10 of KSPDCL SS-6. Feeder tripped on operation of Complete outage Earth fault overcurrent protection. of 220/66 kV At the same time, 220kV Pavagada 06-Oct-20 2 KSPDCL SS-6 - Thirumani line-2 tripped only at 179 NIL GD-1 14:05 hrs (Pavagada) of Pavagada end on operation of KSPDCL Zone-1 distance protection. This resulted in complete outage of 220/66kV KSPDCL SS-6, since the only connected feeder tripped. SLD: Not furnished by KSPDCL Bus configuration and arrangement: Double Bus with Bus coupler
Connectivity Diagram:
400kV Pavagada Bus
220kV Pavagada Bus
DPR Z-1
KSPDC KSPDC KSPDC KSPDC KSPDC KSPDC KSPDC KSPDC L SS-1 L SS-2 L SS-3 L SS-4 L SS-5 L SS-6 L SS-7 L SS-8
OCR/ EF
Tripping of 220kV Thirumani - Pavagada Thirumani line: Pavagada (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped on R-E fault at 14:02:10.236 hrs on operation of DPR, Z1 (15.1 km) protection. Line did not attempt for A/R, as the same was not enabled due to lack of communication channel. Thirumani (KSPDCL) end: As per FIR/ TR, line was hand-tripped.
Deliberation: It was noted that no representative of KSPDCL had come to present their perspective in the meeting. As per tripping files furnished, the triggering incidence was R-E fault because of bird fall on R-phase bus insulator at 66kV Feeder No.10 of Block No.28, of M/s. Adani, connected to 220/66 kV KSPDCL
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Annexure-B SS-6. The 66kV feeder tripped on OCR/ EF protection. Simultaneously, 220kV Thirumani-Pavagada line-2 tripped, only at Pavagada end on operation of DPR, Z1 protection, and did not attempt A/R. This resulted in complete outage of 220/66kV KSPDCL SS-6, since the only connected feeder tripped. During the incidence, KSPDCL SS-6 was feeding around 170MW Solar power. PGCIL-SR2 informed that the Main-1 relay Micom P543 (LDP relay) was observed to have issued trip command in Zone-1 for fault beyond 100%. They informed that Z1 overreach may be due to capacitance effect of cable, which follows the overhead line. It was also noted that even though it was an LDP relay with distance protection as back up, still Zone-1 operated even without carrier fail alarm. In this regard, the philosophy to be followed for Line Differential Relays had been emphasized, viz., Both Main relays should be LDP relays, and each LDP relay should be configured such that Current line differential protection acts as the primary protection, and the inbuilt Z2, Z3, Z4 (reverse zone) of the distance protection act as secondary or back-up protection. Further, as long as communication link is healthy, Z1 of distance protection should be kept disabled, and should be made to become active only upon detection of carrier/ communication link failure.
PGCIL-SR2 mail dated 27.01.20201:
Recommendations: PGCIL-SR2, in coordination with KSPDCL, to review Zonal settings of 220kV Pavagada – Thirumani line at Pavagada end. Further, the philosophy being followed for LDP relays at pavagada end to be brought in line with the SRPC philosophy.
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Annexure-B Triggering incident was failure of Y-ph Metering CT connected to Nandihal - GM Navara line-1. Bus Complete outage bar protection operated at 220kV of 220kV Nandihal 17-Oct-20 Nandihal station and all connected 68 52 GD-1 3 SS, Bijapur SS, and 22:35 hrs elements tripped. There was Indi SS supply failure at 220kV Indi and Bijapur stations, since these station are radially fed from 220kV Nandihal station. Bus configuration and arrangement at 220kV Nandihal SS: Double Bus with Bus coupler
Connectivity Diagram:
Antecedent Conditions: 220 kV Nandihal SS was operating on single bus configuration with all elements connected to 220kV Bus-I due to failure of Bus coupler CT. 220kV Bagewadi-Nandihal lines were under idle charged condition from B.Bagewadi end as per SLDC instructions. 220kV Nandihal-Misabinahal LIS line was under idle charged condition from Nandihal end. 220kV Nandihal-Kudagi -4 line was kept in open condition. 220kV Bijapur and Indi sub stations were radially fed from Nandihal SS.
Complete outage of 220kV Nandihal SS of KPTCL: Tripping of 220 kV Nandihal – GM Navara line-1: Nandihal (KPTCL) end: FIR & EL not furnished. As per DR/ TR, 220kV Nandihal – GM Navar line -1 tripped at Nandihal end in Y-ph on Y-E fault at 22:25:28.021 hrs due to operation of DPR, Z1 (8.8kA, 0.1km) protection and attempted A/R. It was stated in TR that Y-E fault was due to failure of Y-ph metering CT of the line at Nandihal SS. KPTCL informed that the Y-E fault later developed into R-Y fault and hence A/R was unsuccessful. As per DR/ TR, along with the line tripping, at 22.25.28.342 hrs Busbar protection operated at the SS and caused complete outage of the substation.
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Annexure-B GM Navara (Gamesha) end: Tripping files (FIR/DR/EL/TR) not furnished. As per TR of Nandihal end, the fault was sensed at this end in DPR, Zone-2.
Outage of 220kV Indi SS of KPTCL: As per FIR, complete outage of the station was due to supply failure at 220kV Nandihal SS. No TR furnished
Outage of 220kV Bijapur SS of KPTCL: As per FIR, complete outage of the station was due to supply failure at 220kV Nandihal SS. No TR furnished
Deliberations: Triggering incident for the events was failure of Y-ph metering CT of the line at Nandihal SS. As per tripping files furnished, 220kV Nandihal – GM Navar line-1 tripped in Y-ph at Nandihal end on Y-E fault (CT failure) and attempted A/R. But after 266msec the blown up portion of the failed CT reduced the clearance between the R & Y phases of strung auxiliary bus of the same bay and created Bus Fault on R and Y phases causing BBP operation. Due to the R-Y fault, A/R was unsuccessful. At GM Navar end the line tripped in Zone-2. KPTCL informed that during the incidence PLCC problem was there and hence carrier was not sent from Nandihal end. 220kV Indi and 220kV Bijapur SS were being radially fed from 220kV Nandihal SS, and hence lost supply. Generation loss of 68 MW was reported during the incidence. It was also observed that DR and EL of protection relays to be properly configured for recording all requisite digital & analog signals. KPTCL also informed that the failed CT was not yet replaced and hence the bay was yet to be normalised. Bus coupler CT was also not restored and hence the station was still on single bus operation. Remedial measures taken by KPTCL: It was reported by M/s. Gamesa Ltd. that the PLCC was restored and AR was in service for Nandihal-GM Navar Line-1 &2.
Recommendations: M/s. Gamesa Ltd./KPTCL to restore Double bus operation at 220kV Nandihal SS after replacing failed bus coupler CT. M/s. Gamesa Ltd./KPTCL to submit Equipment failure report for failed CT to CEA with a copy to SRPC.
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Annexure-B Triggering incident was jumper cut in 220kV Jurala-Veltoor line. At the same time 220kV Lower Complete outage Jurala- Veltoor, 220kV of 220kV Lower 31-Oct-20 Lower Jurala- Jurala lines-1, 2 & 3 20 NIL GD-1 4 Jurala GS of 04:23 hrs tripped. Running units at Lower TSGENCO Jurala tripped due to loss of evacuating lines resulting in complete outage of Lower Jurala station. SLD: The single line diagram of 220 kV Lower Jurala as furnished by TSGENCO is attached at the end.
Bus configuration and arrangement: Double Busbar arrangement
Antecedent Conditions: 6 units were in service at 220kV Lower Jurala SS with a generation of 130MW.
Connectivity Diagram:
Complete outage of 220kV Lower Jurala GS (TSGENCO): As per FIR, all 6 Nos units and 4 Lines at LJHEP tripped due to B-E fault on 220kV Jurala – Veltoor line (3rd tower conductor B phase snapped). As per FIR 220kV lower Jurala – Jurala lines tripped due to DPR Zone-2/ Zone-3 operation. As per DR of Feeder-3, line tripped at LJHEP end at 04:24:32.101 hrs. As per EL of Line-1, line tripped at LJHEP end in 3-ph at 04:23:09.150 hrs. DR/ EL do not indicate the type of protection that operated. TR not furnished.
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Annexure-B Deliberations: It was noted that no tripping report detailing the sequence of events that led to complete outage of Lower Jurala Station had been submitted. It was also noted that TSGENCO representatives were not able to properly explain the cause of various trippings that culminated in the GD of Lower Jurala. Triggering incidence was snapping of B-ph jumper of 220kV Jurala-Veltoor line at Tower -3 near 220kV Jurala SS. TSTRANSCO informed that snapping of B-ph jumper effectively created an open conductor fault for Jurala end and L-G fault for Veltoor end, which led to tripping of following lines: 220 kV Jurala – Veltoor S/C line at Jurala end on operation of non-directional earth fault protection. 220kV Lower Jurala – Veltoor line at Veltoor end on operation of non-directional earth fault protection. 220 kV Lower Jurala – Jurala lines – 1 & 2 & 3 at Lower Jurala end on operation of non-directional earth fault protection. Due to loss of evacuation lines, running units at 220kV Lower Jurala PH tripped on over frequency protection. To above, SRPC pointed out that sensitive earth fault protection must be directional, and this DEF protection should be set sufficiently above the imbalance currents that may result due to opening of a phase (like single pole A/R operation, open conductor faults, etc). Further, they should also be properly coordinated with that of adjacent stations. It was observed for the above case that not only the settings of DEF were wrongly set, but were also not coordinated properly. It was also noted that from the DR’s & EL’s furnished by TSGENCO for the lines 220 kV Lower Jurala GS, no event corresponding to DEF operation had been observed.
Recommendations: TSTRANSCO to correct sensitive earth fault settings on all 220 kV lines at all Stations in Jurala Complex (220 kV Upper Jurala GS, 220 kV Lower Jurala GS, 220 kV Jurala SS & 220 kV Veltoor SS) including providing directionality. TSGENCO to configure DR’s & EL’s of all protection relays at their 220 kV Lower Jurala GS for capturing all standard & requisite digital & analog signals.
Triggering incident was CT Blast in Bus-coupler bay at 220 kV Complete outage Narendra SS. All connected of 220kV Narendra 31-Oct-20 elements at 220 kV Narendra NIL 40 GD-1 5 Substation of 23:47 hrs station tripped on Bus bar KPTCL protection resulting in complete outage of the station. SLD: The single line diagram of 220kV Narendra SS as furnished by KPTCL is enclosed at the end.
Bus configuration and arrangement: Double Main & Transfer Bus
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Annexure-B
Antecedent Conditions: All elements were connected to Bus 2 at 220kV Narendra SS since 220kV Narendra-Haveri line was charged through Bus coupler. 220kV Narendra-Haveri line was idle charged from Narendra end through Bus coupler
Connectivity Diagram:
Complete outage of 220kV Narendra SS (KPTCL): As per FIR/ DR/ EL/ TR, all elements connected to 220kV Narendra SS tripped on Y-E fault at 02:16:28. 114 hrs due to operation of BBP (Zone-1 & Zone-2). As per FIR/ TR, all elements connected to 220kV Narendra SS tripped on Y-E fault at 23:45hrs which in turn was due to failure of Y-ph CT of 220kV Bus coupler flash over and oil spillage. EL not furnished. DR & EL - Time sync issue Damaged CT and CB details: 220KV CT Details: Make: BHEL Ration: 1200-600-300/1-1-1-1-1A YOM: 1995 Sl No: 2228021(R-phase), 2228022(Y-phase), 2228023(B-phase) 220KV Circuit Breaker Details: Make: ABB Type: ELF SL-4-1 YOM: 1996 Rated Voltage: 245KV Short Circuit Current: 40KA, 3sec Rated Normal Current: 2000Amps
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Annexure-B SoE as per Tripping Report:
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Annexure-B Deliberations: During the antecedent condition, 220kV Narendra-Haveri line CB had developed air leakage and hence the line was hand tripped. Subsequently, the line was idle charged from Narendra end through Bus coupler CB. All elements at 220kV Narendra SS were connected to single bus (BBP- single Bus zone operation). As per KPTCL’s Tripping Report, at 23:45 hr. Y-ph CT of 220kV Bus coupler flashed over and there was fire due to oil spillage. This resulted in operation of BBP and tripping of all elements connected to 220kV Narendra SS since the station was on single bus operation. The failed CT was of BHEL make and Year of Manufacture is 1995. KPTCL also informed that after detailed inspection, it was found that along with ‘Y’-phase 220KV CT flashover, the ‘R’-phase 220KV CT insulator petticoat was also damaged and found oil leakage in bushing, and 220KV ‘B’-phase CT tank body blackened. Also insulator of 220KV Bus Coupler circuit breaker got damaged. SRPC pointed out that condition monitoring of CTs and all substation equipment need to be properly carried out on regular basis. KPTCL informed that new CT for Bus coupler was procured and on completion of the replacement of the same, double bus operation would be restored. Remedial measures taken by KPTCL: New CTs had been procured for Bus coupler bay and CT replacement work was under progress. After CT replacement, double bus operation would be restored at Narendra Substation. GPS time synchronization issue with the Bus Bar Protection scheme was observed from the DR. GPS time synchronizing device was provided at Narendra under R&U works. However, SIFANG make Bus Bar Protection relay was not synchronized with GPS clock. Necessary support from OEM was being arranged for attending this issue.
Recommendations: KPTCL to expedite restoration of double bus operation, and ensure time synchronisation of relays at their 220/ 110 kV Narendra SS..
Triggering incident was failure of R-Ph LA of 220 KV VSS - Gajuwaka_AP line at VSS end. Due to non-tripping of line at 220kV VSS Complete Outage end, fault was cleared by tripping of 220kV VSS and 07-Nov-20 of all connected elements at NIL 153 GD-1 6 220kV Parawada 16:06 hrs remote end. This resulted in SS of APTRANSCO complete loss of supply at 220kV VSS. Since 220kV Parawada was radially fed from 220kV VSS, there was complete loss of supply at 220kV Parawada SS. SLD: The single line diagram of 220kV VSS as furnished by APTRANSCO is enclosed at the end.
Bus configuration and arrangement at 220kV VSS: Double Bus with Bus coupler Bus-1: 220kV VSS - MRS line-1, 220kV VSS - Paravada line, 220kV VSS – Kakinada line, 220kV VSS – Kalpaka lines-1 & 2, 220kV VSS – Gangawaram line, 220kV VSS – Gazuwaka line-1 Bus-2: 220kV VSS - Pendurthi lines 1 & 2, 220kV VSS MRS line - 2
Antecedent Conditions: 220kV Parawada-Anark Aluminium line was under outage.
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Annexure-B Connectivity Diagram:
Complete Outage of 220kV VSS (APTRANSCO): As per FIR, all elements connected to 220k VSS tripped on R-E fault at 16:06 hr. It was stated that the earth wire connected between 220KV VSS end gantry peak to PGCIL end gantry peak snapped and fallen on Y & B-Phases of PGCIL-1 feeder. At the same time R-Phase LA of 220KV VSS - Gajuwaka feeder failed and all the feeders connected to 220KV BUS-1&2 tripped. As per DR of 220 kV VSS - Gazuwaka line at VSS end, fault current was observed to be persisting for 700 msec, and the tripping occurred at 16:02:26.675 hrs. No Bus DR / EL/ TR submitted. Line DR submitted.
Complete Outage of 220/ 132kV Parawada (APTRANSCO): As per FIR, complete outage of 220/ 132kV Parawada occurred due to incoming supply failure at 220kV VSS. 220kV Parawada was radially being fed from 220kV VSS.
Tripping of 400/ 220kV ICT-1 & 2 at Gazuwaka: Gazuwaka (PGCIL-SR1): As per FIR/ DR/ EL/ TR, ICT-1 & 2 tripped at 16:06:18.380 hr. on operation of directional overcurrent protection. (Td~ 700msec)
Tripping of 220kV VSS – MRS line-1 VSS (APTRANSCO) end: As per FIR/DR, line tripped on R-E fault at 16:05:23.509 hr due to DPR, Z3 operation. DR time scale was limited to 200 msec. As such, Zone-3 pickup not captured in DR hence Td could not be verified. This should be increased to 500msec pre fault and 2 sec post fault. EL/ TR not furnished.
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Annexure-B ******************************************************************************* Analysis of DRs submitted by APTRANSCO: 1. 220kV VSS-Gazuwaka line: Gazuwaka end: As per DR, line tripped on R-E fault at 16:03:33.838 hr. due to DPR, Z2 operation. 2. 220kV VSS-MRS lines-1 & 2: VSS end: As per DR, line tripped on R-E fault at 16:05:50.372 hr due to DPR, Z3 operation. (Td could not be calculated due to restricted time scale) MRS end: 3. 220kV VSS-Kakinada line: Kakinada end: As per DR, line tripped on R-E fault at 15:03:41.870 hr. on operation of DPR Zone-2. (Td ~ 500msec) Time sync issue 4. 220kV VSS Kalpaka lines – 1& 2: Kalpaka end: As per DR, line tripped on R-E fault at 16:06:18.229 hr. on operation of DPR Zone-2. (Td ~ 350msec) 5. 220kV VSS Penduruthy lines – 1& 2: Penduruthy end: As per DR, line tripped on R-E fault at 15:02:51.100 hr. (line-1) and 16.05:31.241hr. (line-2) on operation of DPR Zone-2. (Td ~ 350msec) Time sync issue
******************************************************************************* Deliberations: The triggering incidence for the events was dropping snapped earth wire, connected between 220KV VSS end gantry peak to PGCIL end gantry peak, on Y&B-Phases of PGCIL-1 feeder. At the same time, R-Phase LA of 220KV VSS - Gajuwaka feeder failed. This resulted in R-E fault on 220kV VSS – Gajuwaka_AP line. The fault was cleared by operation of DPR Zone-2 at Gazuwaka_AP end. At VSS end Main-1 and Main-2 relays did not operate (only Main-2 relay distance pick up was observed) and hence the fault was cleared by tripping of all 220kV lines from remote end on operation of DPR Zone -2. Since 220kV VSS- Gazuwaka line did not trip at VSS end, fault current was continued to be fed and finally 400/ 220kV ICTs at Gazuwaka tripped on HV side directional O/C protection after a time delay of 700msec. APTRANSCO stated that though the fault current was high, voltage dip was not noticed. Due to this, perhaps the fault location did not come in the relay zone. This resulted in complete outage of 220kV VSS. As 220/ 132kV Parawada SS was radially fed from VSS, the event resulted in complete outage of 220/ 132kV Parawada SS as well. APTRANSCO informed that at the time of above event, earth resistance at 220kV VSS was observed to be very high (nearly 3 ohm), hence, during the R-E fault, there was no dip in voltage; thus the fault was not detected in Zone-1 (even though location of fault was within zone-1 reach). Subsequently, the earth resistance was brought down to 0.35 ohm. SRPC pointed out that earth resistance of 220kV stations need to be measured regularly, and ensured that the same is within permissible limits. Proper earthing and connections of LA shall also be ensured.
Remedial Measures taken: APTRANSCO informed that non-operation of distance relays was due to insufficient dip in voltage due to improper substation earthing and the same was rectified. The earth resistance value was subsequently brought down to 0.35 ohm.
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Annexure-B Triggering incident was tripping of 230kV Betam - TTGIS Line on operation of OV st-1 protection at Complete Outage 12-Nov-20 Betam end. Due to tripping of the of 230 kV Betam 42 NIL GD-1 7 12:03 hrs only connected line, there was Wind Energy complete loss of supply at 230kV Betam Wind Energy resulting in wind generation loss of 42MW.
Bus configuration and arrangement: Double Bus with Bus coupler
Connectivity Diagram:
Tripping of 230kV Tuticorin PS – Betam wind line: Tuticorin PS (PGCIL-SR-2) end: As per FIR/ DR/ EL/ TR, line tripped at 12:03:18.064 hr. on receipt of DT from remote end.
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Annexure-B Betam wind end: As per FIR, line tripped at 12:03 hrs on Overvoltage. IPP informed that during the time engineer was working in troubleshooting of Battery charger. As per EL line tripped at 12:03:18.046 hr. on Dead Zone trip protection. As per TR during Battery Charger Earth fault relay replacement work, DC Power supply was cut off at Bus bar CRP and BB Protection dead zone trip occurred on Line Bay and DT was sent to TTPS end. Due to this, Line -01 21M1 Protection under voltage – 2 picked up, both ICT-01 & 02 also tripped.
Deliberation: As per tripping files furnished, the triggering incidence for the event was cutting off of DC Power supply to Bus bar CRP. This led to BB Protection dead zone trip and Under Voltage (Stage-II) Protection trip of 230kV Tuticorin PS – Betam wind line at Betam end and DT was sent to Tuticorin PS. Tripping of the only evacuating line led to complete outage of 230kV Betam wind Station.
SRPC expressed concern that all solar and wind IPPs are mostly connected by single circuit line, without auto-reclosure. Hence, any fault on the line/bus would trip the line and results in GD. It was suggested to ensure reliability while planning connectivity to RE. In this connection, SRLDC was requested to give suitable feedback to NLDC/ CEA on the need to ensuring reliability while planning connectivity to RE.
As per the information received, all Complete Outage connected lines tripped at 230kV 13-Nov-20 of 230 kV MAPS of MAPS due to BBP operation 210 NIL GD-1 8 03:09 hrs NPCIL resulting in complete loss of supply. SLD: The single line diagram of 230 kV MAPS GS as furnished by NPCIL is attached at the end:
Bus configuration & arrangement: Main (Sectionalised) bus with transfer bus arrangement.
Antecedent Conditions: BUS B&C were in service All the 230kV lines were in service IGCAR TR-1&2 were in service BHAVINI feeder was in service Unit-1 S/D, Unit-2 was operating 220MW(e)
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Annexure-B SUT-1&2 were in service, TG-2, GT-2 & UT-2 were in service.
Tripping of 230kV MAPS – SP Koil line- 1: MAPS (NPCIL) end: No Tripping files furnished. NPCIL informed that line tripped at 03:10 hrs on R-E fault due to operation of DPR Zone-1 and A/R was not attempted. SP Koil (TANTRANSCO) end: As per TR, line-1 tripped at 03:10 hrs on R-E fault due to DPR, Z1 (A/R) operation, and line successfully auto-reclosed. As per DR/EL, line tripped in R-ph at 02:06:12.240 hrs on R-E fault due to DPR, Z1 operation. But events corresponding A/R operation including successful re-closure were not recorded in either of them. Time sync issue.
Tripping of 230kV MAPS – SP Koil line- 2: MAPS (NPCIL) end: No Tripping files furnished NPCIL informed that line tripped at 03:10 hrs on R-E fault due to operation of DPR Zone-1 and A/R was not attempted. SP Koil (TANTRANSCO) end: As per TR, line-1 tripped at 03:10 hrs on R-E fault due to DPR, Z1 (A/R) operation, and line successfully auto-reclosed. As per DR/EL, line tripped in R-ph at 03:15:23.165 hrs on R-E fault due to DPR, Z1 operation. But events corresponding A/R operation including successful re-closure were not recorded in either of them. Time sync issue.
Tripping of 230kV MAPS – Echur line: MAPS (NPCIL) end: No files furnished Echur (TANTRANSCO) end: As per FIR/ TR, line was holding at Echur end.
Tripping of 230kV MAPS – Acharapakkam line: MAPS (NPCIL) end: No files furnished Acharapakkam (TANTRANSCO) end: As per FIR/ TR line was holding at Acharapakkam end.
As per MAPS e-mail dated 28.01.2021: Unit-2 was operating normal at about 223 MWe. On 13.11.2020, heavy rain, lightning and thunder were observed in the vicinity of Kalpakkam. At 03:09 hrs., 230 kV SP Koil line-1 and line-2 main protection trip & lock out alarm appeared and both lines tripped. Within 300 milli secs, CVT of R- phase of Bhavini feeder failed and initiated 230 kV Bus-B differential protection resulting in opening of all the breakers connected to Bus-B (GT-2, Line 3 &4, Bhavini, IGCAR TR-2, SUT-1) and tie breaker CB- 6. UT-2 LV breaker also tripped on protection and resulted in unit trip. Event Sequence: Line-1 &2 got tripped on Rph Zone-1 EF Line-3&4 got tripped on bus bar protection
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Annexure-B
Deliberations: MAPS informed that at 03:09 hrs R-E fault occurred on 230kV MAPS – SP Koil line-1 & 2. The fault was sensed in Zone-1 at both ends and successfully autoreclosed at SP Koil end. Within 300msec, R-ph CVT of 230kV MAPS – Bhavini line failed resulting in operation of BBP for Bus-B, tripping all Bus-B connected lines. Tripping of 230kV Bus –B along with tripping of 230kV SP Koil line-1, which was the only source on 230kV Bus C, resulted in complete outage of 230kV MAPS GS. MAPS stated that autoreclosures would be enabled, before March 2021.
Remedial action taken: CVTs were provided in the R &B phases of BHAVINI feeder. B phase CVT was used for line charge indication. R phase was not used for any protection or metering. Hence R phase CVT was removed and B phase CVT was replaced with spare.
Triggering incident was failure of R phase CB limb of 230kV Checkanurani- Nallamanayakkan Patti line at Checkanurani end. LBB of 230kV Checkanurani – Complete Outage Nallamanayakkan Patti line of 230 kV 16-Nov-20 operated at 230kV Checkanurani NIL NIL GD-1 9 Checkanurani SS of 13:25 hrs end resulting in the operation of TANTRANSCO Bus-1 BBP. Due to this, all connected elements at 230 kV Checkanurani SS tripped, since all the elements were connected only to Bus-1 during antecedent conditions. SLD: The single line diagram of 230kV Checkaurani SS as furnished by TANTRANSCO is enclosed at the end.
Bus configuration and arrangement: Double Bus with Bus coupler
Connectivity Diagram:
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Annexure-B
Antecedent Conditions: All elements were connected to Bus-1 at 230kV Checkanurani SS due to Bus coupler CT failure (failed since March 2020).
Tripping of 400/ 230kV ICT-1, 2 & 3 at Madurai: Madurai (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR ICT-1 & 2 tripped on 230 kV side at 13:24:50.508 hrs due to LBB operation. As per FIR/ DR/ EL/ TR ICT-3 tripped on 230 kV side at 13:24:52.377 hrs due to operation of back-up earth fault protection.
Complete outage of 230kV Checkanurani SS of TANTRANSCO: As per FIR/ TR, all elements connected to 230kV Checkanurani SS tripped at 13:25 hr. on operation of LBB protection. It was stated in FIR that R-phase Breaker limb blasted in 230kV Checkanurani – NLMPatty feeder. Hence the line fault was not cleared and led to operation of LBB protection. As per DR/EL of 230 kV Checknaurani – NLMPatty line at Checknaurani end, line tripped at 12:24:50.500 hrs due to R-ph LBB operation. Analog & Digital signals of DR not named properly.
Deliberations: During antecedent conditions, all elements were connected only to Bus-1 at 230kV Checkanurani SS. TANTRANSCO informed that triggering incidence was R-E fault on 230kV Checkanurani - Nallamanayakkanpatti line. During the fault, distance protection of the line operated and at the same time R phase CB limb of 230kV Checkanurani-Nallamanayakkanpatti line at Checkanurani end blasted. This resulted in LBB operation at 230kV Checkanurani end causing operation of Bus-1 BBP. Due to this, all connected elements at 230kV Checkanurani SS tripped, as all the elements were connected only to Bus-1 during antecedent conditions. However, ICT#3 at 400kV/230kV Madurai was not tripped. Due to non-tripping of ICT#3, there was fault feed even after the tripping of other elements connected to Bus-1. Subsequently, ICT#3 got tripped on operation of LV side backup earth fault protection. No load loss during this event was reported. The 230KV breaker Rph limb got blasted and failed to clear the line fault within permissible time. Hence, LBB operated. During the site inspection and events downloaded from 230KV Checkanurani-Nallamanayakkanpatti feeder it was found that R-Ph Limb tried for opening after 37msec via carrier aided trip but could not be opened even after 200msec, hence LBB operated. The entire fault cleared only after 331msec. Remedial Measures Taken:
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Annexure-B In order to set right the LV3 tripping issue of 400/ 230kV ICT-1, necessary line clear was availed at 14.20Hrs (on 17.11.2020) and tested the Busbar protection relay. It was observed that output contact of LV3 was defective. The same was replaced with available spare contacts and actual tripping extended to LV3 at PGCIL end and found satisfactory. Failed CB limb of 230kV Checkanurani- Nallamanayakkanpatti line was replaced 07.12.2020. TANTRANSCO informed that Bus coupler CT at 230kV Checkanurani SS was replaced on 18.12.2020 and double bus operation was put into service.
In this connection, TANTRANSCO was asked to submit equipment failure report, w.r.t. the failed CB at 230kV Checkanurani SS to CEA with a copy to SRPC.
During antecedent condition, due to outage of 220kV Kalamasserry - Idukki line-1 and 2, 220kV Kalamasserry SS was radially fed from 400kV/220kV Kochi_PG SS and flows in 220kV Kochi_PG - Kalamasserry line-1 and 2 were around 195MW each respectively. Complete Outage As per the report submitted, of 220 kV 17-Nov-20 triggering incident was B phase to 10 NIL 390 GD-1 Kalamasserry SS of 12:41 hrs Earth fault in 220kV Kochi_PG - KSEB Kalamasserry line-1. After the tripping of 220kV Kochi_PG - Kalamasserry line-1, 220kV Kochi_PG - Kalamasserry line-2 got overloaded. 220kV Kochi_PG - Kalamasserry line-2 tripped on operation of DEF protection as per IDMT curve at Kochi_PG end and was holding at Kalamasserry end. Bus configuration and arrangement: Double Bus arrangement
Antecedent Conditions: 220/ 110kV Kalamasserry SS was under single Bus operation. 220kV Idukki - Kalamasserry line – 1 & 220kV Idukki - Kalamasserry line – 2 were under shutdown and 220kV Kalamassserry SS was radially fed from 400/ 220kv Kochi_PG.
Connectivity Diagram:
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Annexure-B
Tripping of 220kV Kochi_PG – Kalamasserry line-1: Kochi_PG (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped in B-ph at 12:41:01.735 hr. on B-E fault due to DPR, Z1 (A/R, 9.1km, 5.38kA) operation, and tried to auto-reclose after about 1 sec, but tripped in 3-ph due to persisting fault. Kalamasserry (KSEBL) end: As per FIR/ DR/ EL/ TR line tripped in B-ph at 12:41:01.738 hr. on B-E fault due to operation of DPR Zone-1, attempted A/R but tripped in 3-ph due to persisting fault. (10.4km; 7.5kA)
Tripping of 220kV Kochi_PG – Kalamasserry line-2: Kalamasserry (KSEBL) end: As per FIR/ DR/ EL/ TR, line was kept holding from Kalamasserry end. Kochi_PG (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped at 12:41:02.833 hrs on B-E fault due to DEF operation. Zone-2 start signal (12:41:01.789 to 12:41:01.814) should have reset DEF. That is DEF protection was not observed to be co-ordinated with DPR protection. Because DEF protection started right at the time line-1 tripped in B-ph on A/R, not when it tripped in 3-ph due to unsuccessful A/R.
Deliberation: The triggering incidence for the event was B-E fault in 220kv Kochi_PG – Kalamasserry line-1. Line-1 tripped in B-ph at both the ends and attempted A/R, but tripped in 3-ph due to persisting fault. The Line-2 tripped only at Kochi PG end due to DEF operation when Line-1 tripped in B-ph due to A/R operation. PGCIL-SR2 informed that in the antecedent condition both the lines were carrying 390MW. When line attempted A/R in B-ph the entire B-ph current shifted to line-2 (nearly 800A) and in neutral there was around 300A current hence DEF was not reset. To this, SRPC pointed out that DEF protection should be set sufficiently above the expected maximum load current under all operating scenarios. Further, instead of coordinating it with DPR (Z3) operation, it was suggested that suitable PSL logic shall be built in DEF relay at Kochi end ensuring that the same is blocked during DPR operation, and is enabled only when DPR does not pick up. SRLDC pointed out that KSEBL shall plan proper load management in situations when 220kV Kalamasserry SS have to be operated radially from Kochi_PG, as tripping of one among 220kV Kochi_PG – Kalamasserry lines would result in tripping of other line due to overloading. Suitable SPS, if
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Annexure-B needed, shall be put into service.
Recommendations: PGCIL-SR2 to revise DEF settings of 220kV Kalamasserry – Kochi_PG such that DEF protection will not operate for maximum expected load current under all operating scenarios. Further, DEF should be kept blocked during DPR operation; and DEF should be enabled only when DPR does not pick up.
As per the information received, all connected lines tripped only at Complete Outage 25-Nov-20 11 Bhavini end due to Over voltage NIL 70 GD-1 of 230 kV BHAVINI 22:53 hrs resulting in complete loss of supply. Details are awaited. SLD: The single line diagram of 230kV Bhavini SS is enclosed at the end.
Bus configuration and arrangement: Double Bus arrangement
Antecedent Conditions: Grid voltage near Bhavini was high on account of widespread load shedding due to Nivar Cyclone.
Tripping of 230kV Bhavini – Siruseri line-1: Bhavini end: As per FIR/ TR, line tripped at 22:53 hrs due to OVR operation. As per DR/ EL, lines tripped at 22:53:40.181 hr. (144kV, 145kV & 143kV). But signals corresponding to OVR operation were not found in DR/ EL. Also DT sent signal was not found. Siruseri (TANTRANSCO) end: As per FIR, lines were holding at Siruseri end.
Tripping of 230kV Bhavini – Siruseri line-2: Bhavini end:
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Annexure-B As per FIR/ TR, line tripped at 22:53 hrs due to OVR operation. As per DR/ EL, lines tripped at 22:53:40.181 hrs (144kV, 145kV & 143kV). But signals corresponding to OVR operation were not found in DR/ EL. Further, DT signal was not observed to be sent to remote end. Siruseri (TANTRANSCO) end: As per FIR, lines were holding at Siruseri end.
Tripping of 230kV Bhavini – Arni line-1: Bhavini end: As per FIR/ TR line tripped at 22:53 hrs due to OVR operation. As per DR/ EL, line tripped at 22:53:45.968 hrs (142kV, 143kV & 142kV). But But signals corresponding to OVR operation were not found in DR/ EL. Also DT sent signal was not found. Protection operated not indicated in DR/ EL. Arni (TANTRANSCO) end: As per FIR line was holding at Arni end.
Tripping of 230kV Bhavini – Arni line-2: Bhavini end: As per FIR/ TR line tripped at 22:53 hrs due to OVR operation. As per DR/ EL, line tripped at 04:18:33.035 hrs (142kV, 143kV & 142kV). But signals corresponding to OVR operation were not found in DR/ EL. Also DT sent signal was not found. Protection operated not indicated in DR/ EL. Arni (TANTRANSCO) end: As per FIR line was holding at Arni end.
Tripping of 230 kV Bhavini – Kanchipuram line-1: Bhavini end: As per FIR/ TR line tripped at 22:53 hrs due to OVR operation. As per DR/ EL, line tripped at 22:53:45.626 hrs (144kV, 144kV & 144kV). But signals corresponding to OVR operation were not found in DR/ EL. Also DT sent signal was not found. Protections operated not indicated in DR/ EL. Kanchipuram (TANTRANSCO) end: As per FIR, line was holding at Kanchipuram end.
Tripping of 230 kV Bhavini – Kanchipuram line - 2: Bhavini end: As per FIR/ TR line tripped at 22:53 hrs due to OVR operation. As per DR/ EL, line tripped at 04:18:33.035 (144kV, 144kV & 144kV). But signals corresponding to OVR operation were not found in DR/ EL. Also DT sent signal was not found. Protections operated not indicated in DR/ EL. Kanchipuram (TANTRANSCO) end: As per FIR, line was holding at Kanchipuram end.
Deliberation: In the antecedent conditions, grid voltage near 230kV Bhavini SS was high on account of widespread load shedding due to Nivar Cyclone. At 22:53 hrs Overvoltage appeared at Bhavini SS and tripped all connected lines – 230kV Bhavini – Siruseri lines – 1 & 2, 230kV Bhavini – Arni lines – 1 & 2, 230kV Bhavini - Kanchipuram lines -1 & 2. Bhavini informed that Overvoltage setting of 110%, 5 sec was adopted at 230kV Bhavini SS and it was
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Annexure-B not configured to send DT. SRPC pointed out that OVR gradings of transmission lines come to rescue if only the Over Voltage conditions are temporary, and not sustaining. In the instant case, due to non-commencement of generation from Bhavini units, the reactive power support which is generally expected of generating units was also not available. Under these conditions, over voltage conditions were prevalent due to cyclone Nivar caused load shedding. As same OVR gradings were adopted on all lines emanating from Bhavini, they got tripped simultaneously resulting in comlete station outage. Accordingly, Bhavini was asked to revise OVR gradings of various lines in such a way that time settings and over voltage settings are sufficiently staggered so that all evacuating lines trip in the order as per their respective reactive power (capacitive vars) contribution, which in turn may be realized by suitably staggering their time settings and over voltage settings. Further, OVR operation shall be configured to send DT to the remote end of the lines. Bhavini was also asked to configure DR’s and EL’s of all protection relays are configured properly with all required protection (digital & analog) signals.
Recommendations: Bhavini to ensure that DR’s and EL’s of all protection relays are configured properly with all required protection (digital & analog) signals. Zone-1 distance protection of 220kV Kadra - Kaiga line operated at 220kV Kadra end and LBB operated since the line was under NFBC during antecedent condition. Due to operation of LBB Complete outage 02-Dec-20 protection, all the elements 12 of 220kV Kadra PH NIL 39 GD-1 14:01 hrs connected to Bus-1 tripped at of KPCL 220kV Kadra. Since all the elements were connected only to Bus-1 during antecedent condition, there was complete loss of supply. There was no generation at Kadra during this event Bus configuration and arrangement: Single bus arrangement
Antecedent Conditions: Generating Units -1 & 2 & 3 was under shutdown. Kadra-Kaiga 220KV Line was taken out of service on 02/12/2020 at 08:31hrs for maintenance activities by Kaiga generating Station through SRLDC code 12/219. As part of line isolation NFBC was issued to Kaiga on 02.12.2020. Kaiga side Earth switch of the line was closed at 08:46hrs vide message No 887 and Kadra side Earth switch was closed at 09:05hrs vide message no: 969.
Connectivity Diagram:
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Annexure-B
Tripping of 220kV Kadra – Kaiga line: Kadra (KPCL) end: As per FIR / DR/ EL/ TR, 3-ph fault occurred on the line at 14:00:58.046 hrs, and DPR, Z1 (Ia- 186 A, Ib- 227, Ic-270A, In- 683A) & SOTF protections operated. However, it was noted that the fault current was persisting, and the line tripped in 3-ph at 14:00:58.334 hrs. It was stated in FIR that LBB protection operated for this line, and led to tripping of all other lines in SS (as they were on single bus operation). Kaiga (NPCIL) end: As per FIR / DR/ EL/ TR, 3-ph fault occurred on the line at 14:00:58.016 hrs, and DPR, Z1 (Ia- 186 A, Ib- 227, Ic-270A, In- 683A) & SOTF protections operated. It was noted that the fault current was persisting up to 14:00:58.336 hrs. Tripping of 220kV Kadra – Kodasalli line: Kadra (KPCL) end: As per FIR, line tripped at 14:01 hr. on operation of LBB protection As per DR, line tripped at 14:00:58.006 hr. (Ia- 260A, Ib- 371A, Ic- 1861A, In-1260A). EL not furnished LBB operation signal not mapped in DR. Kodasalli (KPCL) end: As per FIR, line was kept holding from Kodasalli end.
Complete outage of 220kV Kadra PH (KPCL): As per FIR/TR, 3-ph fault occurred on the line at 14:00:58.046 hrs, and DPR, Z1 (Ia- 186 A, Ib- 227, Ic- 270A, In- 683A) & SOTF protections operated. However, it was noted that the fault current was persisting, and the line tripped in 3-ph at 14:00:58.334 hrs. It was stated in FIR that LBB protection operated for this line, and led to tripping of all other lines in SS (as they were on single bus operation).
Deliberations: As per tripping files furnished, 220kV Kadra - Kaiga line was out in antecedent condition for maintenance activities with earth switch closed at both ends. At 14:00 hrs, the line tripped at both ends on 3-ph fault on DPR, Z1 and SOTF protections. Since the breaker was already in open condition and fault current persisted, this resulted in LBB operation at Kadra end. It was noted that at Kaiga end, the above did not result in LBB operation. KAPS explained that they had provided an additional Isolator towards bus side so that whenever a line is taken on LC, the
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Annexure-B corresponding Bus side isolator is also kept open. Further, their LBB protection also checks for the closed status of CB isolators before issuing trip. On this, KPTCL pointed out that in Micom relays such as P444, spurious SOTF operation such as the above could be avoided by increasing the ∆I settings. PCSC forum opined that presence of fault current in line taken out for LC may be due to induction. During LC, in order to avoid such situations, line CTs may be temporarily earthed on line side as well for LC duration. Unnecessary SOTF operation could be avoided by increasing the ∆I settings in Micom P442 relay.
Recommendations: KPCL to revise ∆I settings in Micom protection relay being used on 220 kV Kadra – Kaiga at Kadra end. KPCL to examine the feasibility of providing an earth switch to line-CT on line side on all 220 kV lines at their 220 Kadra PH, and take steps to provide the same, if feasible.
As per the information received, Complete Outage connected 400kV lines tripped on of 400k V SPIC 05-Dec-20 13 operation of OV St-1 protection NIL 1.5 GD-1 Energy Power 02:48 hrs resulting in complete loss of supply Corporation (SEPC) at 400kV SEPC SLD: Not furnished.
Bus configuration and arrangement: Double Bus with bus coupler
Antecedent Conditions:
Connectivity Diagram:
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Annexure-B
Tripping of 400kV SEPC – Thenampatty line-1: SEPC end: FIR/EL/TR not furnished. As per DR, line tripped at 02:48:10.544 hr. on operation of OVR stage-1 and DT was sent to remote end. (248kV, 252kV, 249kV) Time setting for OVR operation could not be verified. Thenampatty (TANTRANSCO) end: As per FIR/ TR line tripped at 02:48 hr. on operation of OVR protection. As per DR/ EL line tripped at 02:47:57.585 hr. (245kV, 249kV, 247kV) (Td~10sesc) OVR operation could not be verified from DR/ EL. DR / EL to be configured for OVR start, OVR trip and other relevant protection signals.
Tripping of 400kV SEPC – Thenampatty line-2: SEPC end: As per TR, line was kept holding from SEPC end. As per DR line tripped at 02:48:00.797 hr. EL could not be downloaded Thenampatty (TANTRANSCO) end: As per FIR/ DR/ EL/ TR, line tripped at 02:48:10.566 hr. on operation of OVR stage-1 protection and DT was sent to remote end. (Td~ 10 sec) Tripping of 400kV Thenampatty-Kayathar line-2: Thenampatty (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped at 02:48:00.486 hr. on operation of OVR stage-1 protection and DT was sent to remote end. (Td~ 10 sec) (248kV, 254kV, 246kV) Grading to be issued for Thenampatty Kayathar (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped at 02:48:00.511hr. on receipt of DT from remote end.
Tripping of 400kV Kayathar- Kannarpatty line-2: Kayathar (TANTRANSCO) end: As per FIR/ DR/ EL/ TR, line tripped at 02:47:56.555 hr. on receipt of DT from remote end. Kannarpatty (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped at 02:47:56.524 hr. on operation of OVR stage-1 protection (245kV, 254kV, 244kV). (Td~ 6sec) (Grading as per SRPC 2018 – G, - 109%, 6sec)
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Annexure-B
Analysis & Deliberations: As per the tripping files furnished, at 02:47:56 hr. 400kV Kayathar- Kannarpatty line-2 tripped on operation of Overvoltage stage-1 protection at Kannarpatty end and DT receipt at Kayathar end. Subsequently, Overvoltage appeared at Thenampatty and tripped 400kV SEPC - Thenampatty line-1, only at Thenampatty end and at both the ends of 400kV Thenampatty-Kayathar line-2. Later Overvoltage appeared at SEPC end and tripped 400kV SEPC-Thenampatty line-1 from SEPC end also. Finally, 400kV SEPC – Thenampatty line-2 tripped, at Thenampatty end only, on Overvoltage protection. Since SEPC was connected to grid through Thenampatty lines – 1 & 2, the trippings led to complete outage of 400kV SEPC SS. SRPC pointed out that OVR operation shall be configured to send DT and healthiness of communication channel shall be maintained for 400kV SEPC - Thenampatty lines to ensure proper DT communication.
Recommendations: OVR protection signals (Start & Trip for both Stage-I & Stage-II) are to be properly configured in DRs & ELs of protection relays of all 400 kV lines by TANTRANSCO. TANTRANSCO to configure OVR operation to send DT to remote end, and to maintain healthiness of communication channel of 400kV SEPC - Thenampatty lines to ensure proper DT communication.
400kV NLC2 Expansion - NLC TS2 line was under outage during antecedent conditions due to CT and breaker failure at NLC TS2 end. Triggering incident was tripping of Complete Outage 08-Dec-20 400kV NLC2 Expansion -Pugalur 14 of 400 kV NLC2 190 NIL GD-1 07:52 hrs line at Pugalur end on DT Receipt. Expansion Due to tripping of only connected 400kV line, there was complete loss of supply at 400kV NLC2 Expansion and this resulted in a generation loss of 190MW. SLD & Connectivity Diagram:
Bus configuration and arrangement: Double Main and transfer Bus
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Annexure-B
Antecedent Conditions: 400kV NLC TS-2 – NLC TS-2(Exp) line was under shutdown due to CT blast and breaker failure at NLC TS-2 end. Unit-1 at NLC TS-2(Exp) was under shutdown and Unit-2 was generating 190MW.
Tripping of 400kV NLC TS2 (Exp) - Pugalur NLC TS2 Exp (NLCIL) end: As per FIR/ DR/ EL/ TR, line was kept holding from NLC TS-2 (Exp) end. Pugalur (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped at 07:52:02.835 hrs due to DT receipt from remote end.
As per PGCIL-SR2 mail dated 27.01.2021:
Deliberations: It was noted that no representative from NLCIL had come to attend the meeting. As per tripping files furnished, 400kV NLC TS2 (Exp) – Pugalur line tripped, on receipt of DT, only at Pugalur end. This resulted in complete outage of 400kV NLC TS-2(Exp) GS, since it was the only grid connected line. PGCIL-SR2 informed that Zener diode in protection coupler had been replaced so that DT sending would be activated only at 130V (earlier it was at 70V). Also, Tx level at Neyveli end and Rx level at Pugalur end were adjusted. PCSC forum suggested PLCC end-to-end testing for the line. Remedial measures taken by PGCIL-SR2: Zener diode in ETL-14 protection coupler was replaced so that DT would be activated only at 130V (earlier it was at 70V). Tx level at Neyveli end and Rx level at Pugalur end was found to be low and was adjusted. Heat sink portion of power amplifier card was found to be hot compared to others and the same was replaced.
Recommendations: For 400 kV Pugalur – NLC2Exp line, the following shall be carried out by PGCIL-SR2 in coordination with NLCIL: i. End-to-end testing for DT/ permissive & other signals may be ensured by testing at both the ends. ii. Healthiness of PLCC system components (hardware and software) at both the ends to be checked and faulty components to be repaired/ replaced.
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Annexure-B Triggering incident was spurious tripping of 230kV/110kV 100MVA transformer-1 at Villianur SS on WTI (Winding Temperature Trip). At the same time 230kV Villianur Complete Outage connected lines and bus coupler of 230kV/110kV 09-Dec-20 15 tripped on operation of LBB NIL 54 GI-1 Villianur SS of 09:20 hrs protection resulting in the Pondy complete loss of supply at 230kV Villianur SS. 230kV/110kV 100MVA transformer-2 at Villianur SS was under outage during antecedent conditions Connectivity Diagram:
Bus configuration and arrangement: Double bus with bus coupler
Antecedent Conditions: 230/110kV 100MVA Auto Transformer-II was under shutdown since 23.11.2020 due to faulty LV breaker.
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Annexure-B Tripping of 230kV Neyveli TS-2 – Villianur line: Neyveli TS-2 (NLCIL) end: As per FIR/ TR, line was holding at Neyveli end. Villianur (PED) end: As per FIR/ EL/ TR, line tripped at 09:21:38.3813 hrs on operation of LBB protection. The following was stated in TR:
Tripping of 230kV Pondy – Villianur line: Pondy (PGCIL-SR2) end: As per FIR/ TR, line was holding from Pondy end. Villianur (PED) end: As per FIR/ DR/ EL/ TR line tripped at 09:21:34.3813 hrs on operation of LBB protection. EL should be converted into proper PDF
Deliberation: As per tripping files furnished, in the antecedent condition 230/110kV 100MVA Auto Transformer-II was under shutdown since 23.11.2020 due to faulty LV breaker. PED informed that during the incidence, 230/110KV 100MVA Auto Transformer-I tripped on spurious Winding Temperature Trip signal. Subsequently, LBB protection of the ATR-I operated and tripped other connected elements, viz., 230kV Neyveli TS2 – Villianur line and 230kV Pondy – Villianur line. PED informed that to know the cause for actuation of LBB/BB protection for Winding Temperature Trip of Auto Transformer-I, the matter was referred to OEM with all Event Logs and Disturbance Records along with relay settings. After analysing the events, the OEM reported that WTI trip is assigned to TRIPBUS1 in configuration and hence activation of WTI energised the relay output contact (LBB operated) through TRIPBUS1. In busbar scheme, said relay contact of Auto Transformer-I was wired to BusBar protection relay as an input (3Phase LBB operated). Having identified the cause, the OEM reconfigured the said relay contact on 02.01.2021. The output contact concerned, of Auto Transformer-II, was checked and found in order and hence no reconfiguration was carried out. The event led to load loss of 54MW.
Remedial Measures Taken: PED vide email dated 21.01.2021 informed that Winding Temperature Trip circuit of the 100MVA Auto Transformer-I was checked and cleaned all the contact points to avoid spurious tripping again due to
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Annexure-B moisture entry. PED informed that on inspection it was found that WTI trip of ATR-I was assigned to TRIPBUS1 configuration, which was wired to Busbar protection relay as an input (3Phase LBB operated). Hence tripping of ATR-I led to LBB operation. The issue was rectified on 02.02.2021. The output contact concerned, of Auto Transformer-II, was checked and found in order and hence no reconfiguration was carried out.
Triggering incident was ph-ph fault in 230kV Bahour - Karaikal line. At Complete Outage the same time, 230kV Bahour - of 230kV/110kV 31-Dec-20 Pondy line also tripped on 16 NIL 80 GD-1 Bahour SS of 08:23 hrs operation of distance protection. Pondy Due to tripping of both incoming lines, there was complete loss of supply at 230kV Bahour SS.
Connectivity Diagram:
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Annexure-B Bus configuration and arrangement: Double Bus with Bus coupler
Tripping of 230kV Bahour - Karaikal line.: Bahour (PED) end: As per FIR/ DR/ EL/ TR line tripped on R-Y fault at 08:23:09.064 hr. due to DPR, Z1 (2.76km) operation. PED informed that line patrolling was carried out for 230KV Bahour – Karaikal line by M/s Power grid.
Kariakal (PED) end: As per FIR/ DR/ TR line tripped on R-Y fault at 08:23:09.563 hr. on operation of DPR Zone-2 (Ir= 1.197KA, Iy= 1.217KA, 127.1 km, Td~0.5sec). Carrier sent signal observed in DR at Bahour end.
Tripping of 230kV Pondy – Bahour line: Bahour (PED) end: As per FIR/ DR/ EL/ TR, line was kept holding from Bahour end, and was later hand-tripped Pondy (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped on R-Y fault at 08:23:09.093 hrs due to DPR, Z1 operation. Overreaching of distance relay at Pondy end.
Deliberations: The triggering incidence for the events was R-Y fault on 230kV Bahour - Karaikal line. The line tripped at Bahour end due to DPR, Z1 operation at Bahour end and due to DPR, Z2 (0.5 sec) operation at Karaikal end. PED informed that carrier was not received at Karaikal end. At the same time 230kV Pondy – Bahour line tripped at Pondy end due to DPR, Z1 operation. Due to tripping of both the incoming 230kV lines, there was complete loss of supply in 230kV Bahour station. Total load loss reported during the event was 100MW.
As per PGCIL-SR2 mail dated 27.01.2021:
Remedial Measures Taken: PGCIL-SR2 informed that firmware upgradation was carried out for mal-operated distance relay of 230kV Pondy – Bahour line at Pondy end. After upgradation the relay was observed to pick up faults Grid Occurrences discussed in the 94th Meeting of PCSC held on 29th January 2021 34/87
Annexure-B correctly as per zone settings.
II. Details of Grid Incidents: Sl. Details of Event Date &Time Reason Generat Load Category No. ion Loss Loss (MW) (MW)
Tripping of Line tripped only at Alipur end 01-Oct-20 220kV while interchanging the phase 1 - - GI-1 Regulapadu- sequence (online) from RYB to 14:07 hrs Alipur Line BRY. Regulapadu (APTRANSCO) end: As per FIR, line was kept holding from Regulapadu end. Alipur (KPTCL) end: As per FIR/ DR/ EL/ TR, line tripped at 14:09:49.631 hrs due to shorting of one of the trip contacts while RT Staff was interchanging the phase sequence (online) from RYB to BRY with reference to the Regalapadu S/S. No proper DR in PDF format was submitted. KPTCL informed that in Main-2 DR DEF pick up was recorded. But this was not found in the submitted DR.
Deliberations: KPTCL informed that the line tripped due to accidental shorting of trip contacts while RT Staff was interchanging the phase sequence (online) at Alipur, from RYB to BRY, with reference to the Regalapadu S/S. It was informed that phase sequence issue at Alipur had been rectified on secondary side and would be completed on primary side as well in a month’s time.
As per the report submitted, triggering incident was R phase to Earth fault in 400kV Vijayawada - Sattenapalli line. At Vijayawada end, Zone-2 carrier aided protection operated and at Multiple Sattenapalli end, Zone-1 distance Trippings at 03-Oct-20 protection operated. A/r operated 2 - - GI-2 400kV 14:04 hrs at both the ends and line tripped Vijayawada SS due to persistent fault. At the same time, 400kV Vijayawada - VTPS IV line-2 tripped only at Vijayawada end due to suspected mal-operation of Main-2 distance protection and the same needs review.
Tripping of 400kV Vijayawada – Sattenapally line: Vijayawada (PGCIL-SR1) end: As per FIR/ DR/ EL/ TR, line tripped in R-ph on R-E fault at 14:04:56:212 hr. due to operation of DPR Zone-1 (102km, 3.02kA) and attempted A/R. But after A/R dead time line tripped in 3-ph as the fault
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Annexure-B was persisting. Sattenapally (APTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped in R-ph on R-E fault at 14:04:56:202 hr. due to operation of DPR Zone-1 and attempted A/R. But after A/R dead time line tripped in 3-ph as the fault was persisting. (55km, 4.5kA)
Tripping of 400kV Vijayawada – VTS-IV line-2: VTS-IV (APGENCO) end: As per FIR, line was kept holding from VTS-IV end. Vijayawada (PGCIL-SR1) end: As per FIR/ TR line tripped at 14:04 hrs on R-E fault on 400kV Vijayawada – Sattenapally line due to maloperation of Main-2 distance relay. As per DR it was observed that Tie CB only tripped in R-ph at 14:04:56:301hrs., attempted A/R and after A/R dead time tripped in 3-ph. Tie CB tripped in 3-ph but Main CB B-pole only opened at the end of A/R dead time and R-Y pole opened after nearly 2.5 secs after the A/R reclosing attempt.
Deliberations: As per tripping files furnished, the triggering incidence for the events was R-E fault on 400kV Vijayawada – Sattenapally line. The line tripped in R-ph due to operation of DPR Zone-1 and attempted A/R. But after A/R dead time line tripped in 3-ph as the fault was persisting. At the same time, 400kV Vijayawada – VTS-IV line-2 Tie CB tripped in R-ph and attempted A/R. After A/R dead time Tie CB tripped, in 3ph; however, Main CB B-pole only opened, R and Y pole opened after nearly 2.5 sec. PGCIL-SR1 informed that this was due to Main-2 relay mal operation. Later, the relay was retrofitted with new relay on 02.01.2021.
Remedial Measures Taken: PGCIL-SR1 informed that this was due to Main-2 relay mal operation. Later relay was checked and found to be ok. PGCIL-SR1 informed that the old Main-2 relay, ABB Make-Model: REL100, was replaced with new relay ABB make, Model: REL 670 relay on 02.01.2021 at Vijayawada end.
As reported, Pole-1 tripped on Station Inter-Zone protection due to South side CW30Q50 Bay Y-Ph Tripping of HVDC 06-Oct-20 CT blast at Gazuwaka. Pole 2 3 Gazuwaka Pole-1 400 NIL 18:13 hrs Tripped on activation of Protective and Pole-2 Y Block due to disturbance in Inverter side due to sustained commutation failure. Antecedent conditions: In the antecedent condition, Poles - 1 & 2 were carrying 400MW power from East to south.
Tripping of HVDC Gazuwaka Pole-1 (PGCIL-SR1): As per FIR/ DR/ EL HVDC Pole-1 at Gazuwaka tripped at 18:08:27.297 hr. on operation of Station Inter-zone protection due to South side CW30Q50 Bay Y-Ph CT blast. TR not able to download. Time sync issue
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Annexure-B Tripping of HVDC Gazuwaka Pole-2 (PGCIL-SR1): • As per FIR/ DR/ EL, HVDC Pole-2 at Gazuwaka tripped at 18:08:23.095 hr. on activation of Protective Y Block due to disturbance in inverter side due to sustained commutation failure and loss of AC voltage during the blast of CWDQ50 Bay Y-Ph CT blast. TR not able to download. Time sync issue Deliberations: As per the tripping files furnished, triggering incidence for the events was failure of Y-ph CT of South side CWD30Q50 Bay. HVDC Gazuwaka Pole-1 got tripped on operation of Station Inter-Zone protection due to the failure of Y-ph CT. HVDC Gazuwaka Pole-2 got tripped on operation of Y Block protection due to disturbance in inverter side because of sustained commutation failure due to loss of AC voltage during the failure of Yph CT of South side CWD30Q50 Bay. PGCIL-SR1 informed that the failed CT had been replaced and Pole-1 at Gazuwaka was taken back into service.
Remedial Measures Taken: PGCIL-SR1 informed that the failed CT had been replaced and Pole-1 at Gazuwaka was taken back into service.
Triggering incident was R-phase to ground fault in the line at a 07-Oct-20 distance of 0.2 km. from Srisailam 10:37 hrs end due to SRC insulator flashover. Tripping of 220 Line tripped on Zone-1 distance kV Srisailam protection at Srisailam end and 4 Right Bank- Zone-2 distance protection at - - GI-I Nagarjunasagar Nagarjunsagar end. Auto reclose in TS-1 the line is not in service since the 01-Dec-20 line connects two generating 09:20 hrs stations. Non operation of Z2 carrier aided protection at N'sagar end needs review. Tripping on 07-Oct-20 at 10:37 hrs.: Srisailam Right Bank (APGENCO) end: As per FIR/ DR/ EL/ TR line tripped on R-E fault at 10:36:09.814 hr. due to operation of DPR Zone-1 (0.2km, 22.05km). A/R is not enabled since line between two generating stations. Carrier sent signal not observed in DR/ EL but mentioned in TR Time sync issue. Nagarjunasagar TS (TSGENCO) end: As per FIR/ DR/ EL/ TR line tripped on R-E fault at 10:39:06.680hrs due to operation of DPR Zone-2 (75km, 1.9kA, Td~ 300msec). It was stated in TR that in Main-1 relay, Zone-1 operated and in Main -2 Zone-2 operated. Failure of Z-2 CAT Time sync issue
Tripping on 01-Dec-20 at 09:20 hrs: Srisailam Right Bank (APGENCO) end:
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Annexure-B As per FIR, line was kept holding from Srisailam RB end. Nagarjunasagar TS (TSGENCO) end: As per FIR line tripped at 09:20 hr. due to PT fuse failure. As per DR/ EL line tripped at 09:23:39.339 hr. due to operation of DPR Zone-1. Time sync issue
Deliberations: It was noted that 220kV Srisailam RB – Nagarjunasagar line tripped on R-E fault due to operation of DPR Zone-1 at Srisailam RB end and DPR Zone-2 at Nagarjunasagar_TS. A/R was not enabled on this line (connecting two generating stations). TSGENCO informed that carrier was not received at Nagarjunasagar end due to problem with control cable and the same would be rectified. On 01-Dec-2020 the line tripped only at Nagarjunasagar end. It was informed that the maintenance personnel removed the PT fuse mistakenly, which resulted in DPR Zone-1 operation. TSGENCO also informed that GPS was not available at Station and time sync of relays would be ensured in 6 months’ time. To above, SRPC pointed out that under VT fuse fail conditions, DPR operation should be kept blocked. In case of a fault under those conditions, the internal Over Current element should become active to provide protection to the subject line.
Triggering incident was Y-B phase Tripping of fault in 230kV Tirunelveli - 230kV Bus-1 at Udayathur line. LBB of 230kV BUS- 12-Oct-20 5 400/ 230kV 1 at Tirunelveli station operated NIL NIL GI-1 13:45 hrs Tirunelveli due to breaker stuck condition station of PGCIL resulting in tripping of all Bus-1 connected elements. SLD:
Tripping of 230kV Tirunelveli – Udayathur line: Tirunelveli (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped in B-ph on B-E fault at 13:45:33.303 hrs due to operation of DPR Zone-1, and tried to re-close after dead-time of about 1 sec. But due to the persistent nature of the fault (which also developed into Y-B fault), 3-ph trip was issued. Due to this, even though R & Y phase Poles were opened, B-ph pole failed to open successfully. After tripping of line, hunting was observed. From DR, it was observed that BB protection operated at 13:45:35.353 hrs, and DT was sent to the remote end. As per TR, 230KV BUS-I at Tirunelveli tripped on operation of LBB of 206 bay (TNEB owned bay) due to breaker stuck position. Grid Occurrences discussed in the 94th Meeting of PCSC held on 29th January 2021 38/87
Annexure-B
Udayathur (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped in B-ph on B-E fault at 13:45:33.269 hr. and attempted A/R due to operation of DPR Zone-1 (48.8km, 2.99kA). After A/R dead time of about 650 msec., line tripped in 3- ph due to persisting fault. A/R dead-time 650msec. Difference in A/R dead time at both ends.
Tripping of 400/ 230kV ICT-2 at Tirunelveli (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped at 13:45:35.353 hr. on operation of LBB protection.
Tripping of 230kV Tirunelveli – Edamon line-2: Edamon (KSEBL) end: As per FIR/TR, line tripped at 01:45 hrs due to DT receipt from remote end. As per DR/ EL, line tripped in 3-ph at 1:45:35:427 hr. DT receive signal to be configured in DR / EL.
Tirunelveli (PGCIL-SR22) end: As per FIR/ DR/ EL/ TR line tripped at 13:45:35.361 hr. on operation of 230kV Bus-1 LBB protection. LBB operation flag to be configured properly EL & DR.
As per PGCIL-SR2 mail dated 27.01.2021:
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Annexure-B
Deliberations: As per tripping files furnished, the triggering incidence for the events was B-E fault on 230kV Tirunelveli – Udayathur line. The line tripped in B-ph and attempted A/R. During A/R dead time the fault developed into Y-B fault and line tripped in 3-ph due to persisting fault. But due to stuck breaker condition of the line, line did not trip and subsequently LBB protection of 230kV Bus-1 at Tirunelveli operated and tripped all Bus-1 connected elements, viz., 230kV Tirunelveli – Udayathur line, 400/ 230kV ICT-2 at Tirunelveli and 230kV Tirunelveli – Edamon line. PGCIL-SR2 informed that after A/R and tripping of all 3 poles of 230kV Tirunelveli – Udayathur line at Tirunelveli end, Close/Open hunting phenomenon was observed in Y & B poles due to AR close pulse width (150msec) being more than CB close trip operation time (98msec).
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Annexure-B PGCIL-SR2 apprised the forum that the issue had subsequently been rectified by implementing A/R lockout through soft logic when line was tripping on persisting fault. They raised concern regarding frequent faults in 230kV Tirunelveli – Udayathur line. PCSC requested TANTRANSCO to maintain proper ROW along the length of the line. In this connection, TANTRANSCO was also asked to revise A/R ead-time setting from the present 650 msec to 1 sec.
Remedial Measures Taken: PGCIL-SR2 informed that Close/Open hunting phenomenon observed in 230kV Tirunelveli – Udayathur line CB had been rectified by implementing A/R lockout, through soft logic when line was tripping on persisting fault.
As per the report submitted, ICT Tripping of 14-Oct-20 tripped due to operation of PRV 6 400/230 kV ICT-1 - - GI-2 03:49 hrs protection due to contact failure in at Udumalpet the device.
Tripping of 400/230 kV ICT-1 at Udumalpet: Udumalpet (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR ICT-1 tripped at 03:49:39.234 hr. on operation of PRV trip. As per FIR, PRV trip was due to contact failure at device.
Deliberations: As per tripping files furnished, 400/230 kV ICT-1 at Udumalpet tripped at 03:49:39.234 hr. on operation of PRV. PGCIL-SR2 informed that the tripping was due to failure of PRV contact, which in turn was due to aging; and the contact was replaced.
Remedial Measures Taken: PGCIL-SR2 informed that PRV contact failed, due to aging. The contact was replaced.
As per the report submitted, line Tripping of tripped only at Dhoni end on 17-Oct-20 7 400kV Dhoni - operation of CTD while replacing - - GI-2 16:12 hrs Guttur Line CB panel DC source-2 fuses and the same needs review.
Tripping of 400kV Dhoni - Guttur Line: Dhoni (KPTCL) end: As per FIR, line was holding at Dhoni end. Guttur (KPTCL) end: As per FIR/ TR, line tripped at 16:12 hr. on CTD while replacing panel DC source-2 fuses.
Deliberation: KPTCL informed that while checking DC earth fault, DC source-2 fuse failed and while attempting to replace the same, maintenance personnel removed DC source-1 fuse. This resulted in operation of CTD.
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Annexure-B As per the report submitted, ICT#1 Tripping of 21-Oct-20 at RTPS tripped due to operation 8 400/220 kV ICT-1 - - GI-2 15:09 hrs of Buccholz protection and the at Raichur TPS same needs review. SLD:
Tripping of 400/220 kV ICT-1 at Raichur TPS: Raichur (KPCL) end: As per FIR/ TR, 400/220 kV ICT-1 tripped at 15:09 hrs on operation of OLTC Buccholz Protection. It was stated in TR that on inspection, the Buccholz protection was observed to have got operated on spurious fault due to mal-operation of the OLTC Buccholz instrument. DR & EL not furnished.
Deliberations: KPCL informed that 400/220 kV ICT-1 tripped due to mal-operation of contacts of Buchholz relay. They informed that the relay was replaced and configured for triggering of DR & EL (for Buchholz operation).
Remedial Measures Taken: KPCL informed that the Buchholz relay was replaced and configured for triggering DR & EL.
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Annexure-B As reported, 400/220kV ICT-3 at Tripping of Trichur tripped on operation of 86 25-Oct-20 9 400/220 kV ICT-3 A Trip relay along with tripping of - - GI-2 15:17 hrs at Trichur 110kV Madakathara - Vallappad feeder due to insulator decapping. SLD:
Tripping of 400/220 kV ICT-3 at Trichur (KSEBL) end: As per FIR/ EL/ TR, 400/220 kV ICT-3 tripped at 15:15:48.270 hrs on both sides along with the tripping of 110kV Madakkathara – Vallapad feeder. It was stated in TR that the 110 kV feeder tripped due to insulator decapping.
As per KSEBL report dated 23.01.2021:
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Annexure-B
Deliberations: KSEBL informed that 400/ 220kV ICT-3 at Trichur tripped on operation of tertiary earth fault protection during tripping of 110kV Madakkathara – Vallapad feeder. They informed that when normal units of ICTs are in service protection is envisaged through Neutral displacement relay, but when standby unit is taken in service protection is through earth fault relay. On the day of incidence even though standby unit was not in service earth fault protection operated. On inspection it was observed that one terminal of 33kV CT primary was grounded as per scheme. Also the other side for CT primary which was isolated from tertiary winding was also kept connected to ground by means of an earth rod. This had provided a parallel path for a part of fault current during tripping of 110kV Madakkathara – Vallapad feeder. KSEBL vide report dated 23.01.2020 informed that instructions had been given to ensure that earthing shall not be provided on both sides of the tertiary Grounding CT when the same is kept out of service. Triggering of Disturbance record when tertiary earth fault protection acts had been configured.
Remedial Measures Taken: KSEBL vide report dated 23.01.2020 informed that instructions had been given to ensure that earthing shall not be provided on both sides of the tertiary Grounding CT when the same is kept out of service. Triggering of Disturbance record when tertiary earth fault protection acts had been configured.
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Annexure-B As per the report submitted, triggering incident was inadvertent opening of 230kV bus coupler at Multiple 06:03Hr. ICT-1 (400/230KV), ICT- Trippings in 25-Oct-20 2(400/230KV) & ICT-4(400/110KV) 10 - - GI-2 400/230/110 kV 07:07 hrs tripped at 6.18Hr. and ICT-3 Kamuthi SS (400/110KV) tripped at 7.02Hr. and ICT-5(400/110KV) tripped at 7.07Hr. due to over flux protection. Tripping needs review.
Bus configuration and arrangement at 400/ 230/ 110kV Kamuthi SS: 400kV Bus – One and half breaker scheme
230kV Bus – Double bus with bus coupler arrangement
Antecedent conditions: 400kV Karaikudi – Kamuthi Lines -1 & 2 were under shutdown (due to Tie Breaker 89A Isolator - R phase alignment problem) and 230kV Bus coupler was in open condition at Kamuthi SS.
Analysis: As per FIR/ DR/ EL/ TR, 400/110 kV ICT-4 tripped at 06:18:38.093 hrs on operation of Overflux protection. As per FIR/ DR/ EL/ TR, 400/230 kV ICT-2 tripped at 06:18:48.284 hrs respectively on operation of Overflux protection. As per FIR/ DR/ EL/ TR, 400/230 kV ICT-1 tripped at 06:18:48.563 hrs on operation of Overflux protection. As per FIR/ DR/ EL/ TR, 400/110 kV ICT-3 tripped at 07:02:50.092 hrs on operation of Overflux protection. As per FIR/ DR/ EL/ TR, 400/110 kV ICT-5 tripped at 07:07:14.610 hrs on operation of Overflux protection.
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Annexure-B Deliberations: It was noted that in the antecedent condition, 400kV Karaikudi – Kamuthi Lines -1 & 2 were under shutdown (due to Tie Breaker 89A Isolator - R phase alignment problem) and 230kV Bus coupler was in open condition at Kamuthi SS. TANTRANSCO informed that it was their general practice to keep open 230kV bus coupler in morning hours when solar generation picks up so that it is pumped into grid through 400 kV lines/ network. In the instant case, even though the solar generation picked up, since there was no power outflow due to shutdown of 400kV Karaikudi feeders, Overflux protection operated. 400/ 230kV ICT-4, 400/ 230kV ICT-2 & 400/ 110kV ICT-1 tripped at 06.18Hrs, 400/ 110kV ICT-3 tripped at 07.02Hrs and 400/ 110kV ICT-5 tripped at 07.07Hrs. Overflux settings at Kamuthi SS: Stage-I –> 1.1 p.u, 10sec; Stage-II –> 1.2p.u, 0.1 sec. TANRANSCO informed that operators had been instructed not to open 230kV Buscoupler when 400kV Lines are not in service.
As reported 400/220kV ICT-3 at Sriperumbudur tripped on operation of B-phase unit PRV 28-Oct-20 auxiliary protection due to 08:07 hrs problem in the PRV. It was also reported that there was no oil Tripping of spurt out observed in the PRV. 11 400/230 kV ICT-3 - - GI-2 As per the report submitted, ICT#3 at SR'PUDUR at Sriperumbudur tripped due to operation of B phase PRV 16-Nov-20 protection and the same needs 10:13 hrs review. As reported there was no oil spurt out observed in the PRV during the incident. Tripping on 28-Oct-20 at 08:07 hr. As per FIR/ TR, 400/230 kV ICT-3 at Sriperumbdur tripped at 08:07 hrs on operation of B-phase unit PRV auxiliary protection. TANTRANSCO informed that It was due to sluggish operation of PRV operation indicator flag and no oil spurt was observed.
Remedial Measures Taken: The issue was referred to OEM. Transformer oil test (BOTTOM oil sample) done at TNEB R&D LAB on the same day and found in order.
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Annexure-B
Tripping on 16-Nov-20 at 10:13 hrs: As per FIR/ TR 400/230 kV ICT-3 at Sriperumbdur tripped at 10:13 hr. on operation of B-phase unit PRV auxiliary protection. TANTRANSCO informed that the tripping was due to defect in PRV. PRV spring mechanism failed, raised the flag and led to its operation. In this regard, SRPC asked TANTRANSCO to capture PRV operation of ICT’s DR/ EL of protection relays of concenred lines.
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Annexure-B Remedial Measures Taken: Replaced the defective PRV limit switches in all 3-phase units (6No.-2no. in each phase unit of ICT-3) on 16.11.2020. Transformer oil test (BOTTOM oil sample) done at TNEB R&D LAB on the same day and results were in order.
As reported, LC of Bus-1 for general maintenance works was Tripping of availed on the day of the event. 28-Oct-20 12 400/220 kV ICT-4 While testing of metering circuit of - - GI-2 11:29 hrs at Malkaram ICT-4 bay, trip signal was extended by mistake to Malkaram ICT-4, resulting in tripping of the ICT-4.
Tripping of 400/220 kV ICT-4 at Malkaram (TSTRANSCO) end: As per FIR/ DR/ EL/ TR, 400/220 kV ICT-4 tripped at 11:29:17.593 hrs on both sides as trip was extended by mistake during testing of metering circuit of ICT-4
Deliberations: TSTRANSCO informed that in the antecedent condition 400kV Bus-I was taken on LC. HV side Y-ph metering CT fuse of 400/220 kV ICT-4 had failed/low recording-because of blown fuse, and while replacing the fuse, trip was accidentally extended to ICT-4.
Remedial Measures Taken: TSTRANSCO informed that they had instructed MTR wing to exercise due caution while carrying testing and maintenance works.
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Annexure-B ICT#2 and 400kV Alamathy - Thiruvalam line-2 are in the same dia at 400kV Thiruvalam end. During antecedent conditions, Main breaker of ICT#2 at Thiruvalam end was under outage due to CT replacement works. 01-Nov-20 Triggering incident was R phase to - - GI-2 10:57 hrs Earth fault in 400kV Alamathy - Thiruvalam line-2. A/r operated successfully at both the ends and line was holding. At Thiruvalam end, A/R of main breaker only operated and tie breaker tripped. Due to tripping of tie breaker at Thiruvalm end, ICT#2 also tripped. ICT#2 and 400kV Alamathy - Thiruvalam line-2 are in the same dia at 400kV Thiruvalam end. As per the report submitted, during 01-Nov-20 antecedent conditions, Main 12:17 hrs breaker of ICT#2 at Thiruvalam end was under outage due to CT replacement works. Triggering incident was R phase to Earth fault Tripping of - - GI-2 in 400kV Alamathy - Thiruvalam 400/230kV ICT#2 13 line-2. Fault was sensed in Zone-1 at Tiruvalam at both the ends. A/r operated successfully at both the ends and 02-Nov-20 line tripped due to persistent fault. 11:32 hrs At Thiruvalam end, A/r tie breaker did not operate. Due to tripping of tie breaker at Thiruvalam end, ICT#2 also tripped. ICT#2 and 400kV Alamathy - Thiruvalam line-2 are in the same dia at 400kV Thiruvalam end. As per the report submitted, during antecedent conditions, Main breaker of ICT#2 at Thiruvalam end was under outage due to CT replacement works. Triggering 25-Nov-20 incident was operation of OV - - GI-2 21:26 hrs Stage-1 protection at Alamathy end and DT was received at Tiruvalam end. On receiving DT at Thiruvalam end, ICT#2 also tripped due to tripping of tie breaker. As per the DR analysis, Voltages observed at Alamathy end are Vr- 251kV: Vy-251kV. Tripping needs review.
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Annexure-B SLD:
Bus configuration and arrangement at 400kV Thiruvalam: One and Half breaker scheme
Antecedent conditions: ICT-2 and 400kV Thiruvalam-Alamathy line-2 are in the same dia at 400kV Thiruvalam end. The Main breaker (Bay 412) of 400/230kV ICT-2 was under LC for CT replacement works. TANTRANSCO informed that the same would be rectified by Feb 2021. The ICT - 2 was fed through Tie bay (No.411), whereas Alamathy line-2 was fed through Main Bay (No. 410) and Tie-Bay (No: 411). {(410) -----Alamathy line-2 ------(411) ------ICT-2 ----- (412)} Auto reclosure function was kept in OFF condition in Tie Bay (No: 411).
1. Trippings on 01-Nov-20 at 10:57 hrs: Tripping of 400/230kV ICT#2 at Thiruvallam (TANTRANSCO): The Triggering incidence for the event was R-E fault in 400kV Thiruvalam – Almathy line-2. The line Main breaker tripped in R-ph at 10:55:01.245 hr. on operation of DPR Zone-1 and auto-reclosed successfully but Tie CB locked out. As per FIR/ TR, 400/230kV ICT-2 tripped at 10.57 hr. due to tie CB lockout trip.
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Annexure-B 2. Trippings on 01-Nov-20 at 12:17hrs: Tripping of 400kV Almathy – Thiruvalam line-2: Almathy (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped in R-ph at 12:17:10.286 hr. on operation of DPR Zone-1 and attempted A/R. At the end of A/R dead time line tripped in 3-ph due to persisting fault on SOTF operation (3.7kA). Thiruvalam (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped in R-ph at 12:09:13.382 hr. on operation of DPR Zone-1 and attempted A/R. At the end of A/R dead time line tripped in 3-ph due to persisting fault on SOTF operation (65.86km, 4.34kA). Time sync issue.
Tripping of 400/230kV ICT#2 at Thiruvallam (TANTRANSCO): As per FIR/ TR 400/230kV ICT-2 tripped at 12:17 hr. due to tie CB lockout trip.
3. Trippings on 02-Nov-20 at 11:32hr. Tripping of 400kV Almathy – Thiruvalam line-2: Almathy (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped in R-ph at 11:31:53.316 hrs on operation of DPR Zone-1 and attempted A/R. At the end of A/R dead time line tripped in 3-ph due to persisting fault on SOTF operation (65.6km, 4.3kA). Thiruvalam (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped in R-ph at 11:30:14.008 hrs on operation of DPR Zone-1 and attempted A/R. At the end of A/R dead time line tripped in 3-ph due to persisting fault on SOTF operation. Time sync issue.
Tripping of 400/230kV ICT#2 at Thiruvallam (TANTRANSCO): As per FIR/ TR, 400/230kV ICT-2 tripped at 11:32 hr. due to tie CB lockout trip.
4. Trippings on 25-Nov-20 at 21:26 hr. Tripping of 400kV Alamathy – Thiruvalam line-2: Thiruvalam (TANTRANSCO) end: As per FIR/ DR/ EL/ TR, line tripped at 21:26:20.046 hrs on receipt of DT. Alamathy (TANTRANSCO) end: As per FIR/ TR, line tripped at 21:26 hrs on operation of OVR stage-1 (Grading – H, 109%, 5sec).
As per DR/ EL, line tripped at 21:16:29.399 hrs. It was stated in FIR that Main-1 RELAY sensed the V>1, which was recorded in EL but did not issue trip. The relay havd time drift (DR triggered at 21:16 hrs). Since it was old courier version, it did not had provision for GPS connectivity. Main-2 relay indication was "OVR trip". But DR not triggered. This would be set right during next line clear.
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Annexure-B OVR grading could not be verified since OVR pick up signal not configured in DR/ EL. OVR Pick-up and Trip to be configured in DR & EL verifying OVR operation.
Tripping of 400/230kV ICT#2 at Thiruvallam (TANTRANSCO): As per FIR/ TR, 400/230kV ICT-2 tripped at 21:26 hr. due to tie CB lockout trip.
Deliberations: As per tripping furnished, in the antecedent conditions, Main Bay of 400/ 230kV ICT-2 was under LC due to defective CT and ICT-2 was in service through Tie Bay only. TANTRANSCO informed that the same would be rectified by Feb 2021. A/R was disabled for the Tie CB. On all the instances, tripping of 400kV Alamathy - Thiruvalam line-2 due to persistent fault or Overvoltage led to the tripping of 400/ 230kV ICT-2 as well. It was noted that keeping A/R in disabled condition for Tie-CB. Time sync issue was observed at Tiruvalam. TANTRANSCO informed that there was issue with GPS and the same would be rectified. PCSC forum requested TANTRANSCO to ensure proper ROW for 400kV Almathy - Thiruvalam line-2 and to configure OVR start and trip signals in DR/ EL.
Recommendations: TANTRANSCO to enable A/R for both Main-CB & Tie-CB in all dias where one of the elements is a transmission line at their 400/ 230 kV Thiruvalam SS. TANTRANSCO to configure OVR start and OVR trip signals in DR/ EL of the protection relays of all 400kV transmission lines emanating from their 400/ 230 kV Thiruvalam SS.
Tripping of As per the information received, 220kV Bus-1 and 220kV Bus-1 and Bus-2 BBP Bus-2 at operated resulting in the tripping 02-Nov-20 14 400/220/132 kV of all connected elements at NIL 128 GI-1 22:27 hrs Manubolu 220kV Nellore SS. 400kV/220kV (Nellore-AP) SS ICT#1, 2 and 3 at Nellore also of APTRANSCO tripped during this event. SLD:
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Annexure-B Bus configuration and arrangement at 220 kV level of 400/220/ 110 kV Nellore SS of APTRANSCO: 220kV Bus - Double Bus Bar with Transfer Bus arrangement (ALSTOM Make P743 & P741 relays) 220KV Bus-1 220KV Bus-2 315MVA ICT-1 LV 315MVA ICT-2 LV 100MVA PTR-3 315MVA ICT-3 LV 220KV Nellore-2 100MVA PTR-1 220KV Nellore-3 100MVA PTR-2 220KV Rachagunneri-1 220KV Nellore-1 220KV Sullurupet-2 220KV Rachagunneri-2 220KV Sullurupet-1 220KV Sullurupet-3
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Annexure-B Tripping of 400/ 220kV 315MVA ICT-1: As per FIR/ EL/ TR ICT-1 tripped at 22:24:58.313 hr. on operation of HV side overcurrent protection. As per TR, heavy sparks noticed on 220kV Bus-2 side. DR could not be opened from SRLDC website. Tripping of 400/ 220kV 315MVA ICT-2: As per FIR/ EL/ TR ICT-2 at Nellore SS tripped at 22:24:57.769 hr. on operation of 220kV Bus-2 BBP operation. As per TR heavy sparks noticed on 220kV Bus-2 side. DR could not be opened from SRLDC website. Tripping of 400/ 220kV 315MVA ICT-3: As per FIR/ DR/ EL/ TR ICT-3 at Nellore SS tripped at 22:24:57.752 hr. on operation of 220kV Bus-2 BBP operation. As per TR, heavy sparks noticed on 220kV Bus-2 side.
Deliberations: As per APTRANSCO report dated 18.01.2021: Heavy sparks and sound was observed at 400/220/132KV SS Manubolu (Nellore-AP) on 02.11.2020 at 22:25hrs; supply interruption occurred simultaneously. On investigation it was found that, 220kV BUS-2 Busbar Protection operated, causing tripping of all 220KV feeders/ ICTs connected to 220kV BUS-2. The 132KV loads were fed radially from Manubolu SS, the load loss at 440/220/132KV Manubolu SS was 128MW. Also incoming supply failed at 220KV SS Nellore, the load loss at 220/132KV SS Nellore was around 72MW. The total load loss was around 200MW. Due to non-tripping of 220KV Bus coupler breaker, all the 220KV feeders connected to Bus-1 (220KV Nellore-2&3, 220KV Sullurpet-2 & 220KV Rachagunneri-1) were tripped at remote ends in Zone-2. The 315MVA ICT-1 tripped on HV E/F protection. 220kV Bus coupler breaker was hand tripped at 23:22hrs. The 400/220kV 315MVA ICT-1 was charged at 23:26hrs thus energizing 220KV BUS-1, thereby extending supply to the downstream Substations. The 400/220kV 315MVA ICT-2 was charged at 00:36hrs on 03-11-2020 thus energizing 220kV BUS-2. After completion of restoration works, switch yard was inspected and noticed flashover of pilot string insulators at the bottom of 220kV Bus-2 section in R-Phase between 220KV Nellore-3 and 220KV Sullurpet-1 bays. Heavy tracking was observed on pilot string insulator, which was due to the high saline, damp weather and high pollution. The 220KV Manubolu-1 feeder DR & EL at 400/220KV Rachagunneri SS were overflown due to SAS integration works. The reasons for non-tripping of 220kV Bus coupler breaker was explored. It was found that, positive wire from 220KV Bus coupler panel to 220KV Bus bar protection panel got open at the crimped lug at Bus coupler panel. Hence the master trip relay pertaining to Bus coupler in Bus bar protection panel was not operated causing non operation of Bus coupler breaker. The same was rectified, checked the operations of the Bus coupler breaker and found satisfactory. After ensuring the healthiness of control circuit, Bus coupler was taken into service at 12:24hrs on 03-11-2020. Remedial measures taken by APTRANSCO: The Bus shut down was availed on 220kV Bus-2 on 03-11-2020 and the suspected anti fog insulator strings of M/s. WS make were replaced with the available 120KN healthy anti fog disc insulators of M/s. ABI make and 220kV Bus-2 was charged at 18:30hrs on 03-11-2020. The problem with bus coupler breaker was rectified, checked the operations and found satisfactory. After ensuring the healthiness of control circuit, Bus coupler was taken into service at 12:24hrs on 03-11-2020. In this regard, APTRANSCO was asked to make provision for downloading of DR’s and EL’s of all protection relays to a centrallised facility to overcome the issue of over-flowing of DRs.
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Annexure-B As per the report submitted, ICT#4 Tripping of at Shankarapalli tripped due to 07-Nov-20 15 400/220 kV ICT-4 suspected maloperation of PRV - - GI-2 11:47 hrs at Shankarpally protection due to moisture ingress and the same needs review. Tripping of 400/220 kV ICT-4 at Shankarpally (TSTRANSCO): As per FIR/ DR/ EL, 400/ 220kV ICT-4 at Shankarapally tripped at 11:47:52.549 hr. on operation of PRV trip. TSTRANSCO informed that moisture ingress was observed in the PRV relay, cleaned the moisture and charged the ICT.
Remedial Measures Taken: TSTRANSCO informed that ICT-4 tripped due to moisture ingress in the PRV relay; later they had cleaned the moisture and charged the ICT.
As per the report submitted, line tripped on operation of OVR, St-1 protection operated at BTPS end and DT was received at JSWEL Tripping of 400 end. As per the DR of BTPS end, 08-Nov-20 16 kV BTPS-JSWEL voltages observed are: Vr-242kV, - - GI-2 21:45 hrs Toranagallu Vy-239kV and Vb-235kV. Since the voltages at BTPS end are within limits, operation of OV St-1 protection at BTPS end needs review. Tripping of 400 kV BTPS-JSWEL Toranagallu: BTPS(KPCL) end: As per FIR/ DR/ EL/ TR line tripped at 21:45:08.889 hr. on operation of OVR stage-1 protection (Grading A- 111%, 10sec). OVR pick up not configured in DR hence grading could not be verified. As per SRPC OVR grading 2018, 400 kV BTPS-JSW line is the last one to trip.
Toranagallu (JSWEL) end: As per FIR/ DR/ EL/ TR line tripped at 21:45:18.947 hr. on receipt of DT from remote end.
Deliberation: As per tripping files furnished line tripped on operation of OVR stage-1 protection. Voltages at the time of tripping was observed to be 242kV, 239kV, 235kV. From the DR Voltages, it can be seen that there was no Over Voltage conditions. OVR grading could not be verified since OVR_START was not found in DR. Further, before this line could trip, other lines should trip first. Therefore, Tripping was not found to be in order. KPCL informed that R-ph CVT had recorded 256kV and hence OVR trip was issued. PCSC recommended for testing of R-ph CVT and verification of OVR grading implemented at 400kV BTPS GS.
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Annexure-B Recommendations: KPCL to evaluate transient performance of CVTs at BTPS GS and to verify OVR grading implemented at 400kV BTPS GS. KPCL to configure DR’s & EL’s of protection relays of all 400 kV lines at their BTPS station for capturing OVR protection operation (OVR-1_start and OVR-1_trip, OVR-2_trip).
Triggering incident was failure of Y-Phase Suspension Insulator Tripping of 220 string on LV side of Narsapur ICT-1 kV Bus-1 at 220/ 10-Nov-20 17 near 220 kV Bus-1. Bus-1 BBP NIL NIL GI-1 132 kV Narsapur 01:13 hrs operated resulting in the tripping SS of TSTRANSCO of all the elements connected to Bus-1 at 220 kV Narsapur SS. SLD:
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Annexure-B
Bus configuration and arrangement: Double bus arrangement
Tripping of 400/ 220kV ICT-1: As per FIR/ DR/ EL/ TR, ICT-1 tripped at 01:13:09.296 hr. on operation of BBP of 220kV Bus-1.
Tripping of 400/ 220kV ICT-3 at Narsapur (TSTRANSCO) end: As per FIR/ DR/ EL/ TR, ICT-3 tripped at 01:13:09.297 hr. on operation of BBP of 220kV Bus-1.
Deliberations: As per tripping files furnished, BBP of 220kV Bus-1 at Narsapur operated at 01:13 hr. and tripped all Bus-1 connected elements i.e., 400/ 220kV ICT-1 & ICT-3, 220kV Meenajipet line-1 and 100MVA PTR- 1. TSTRANSCO informed that on observation, it was found that there was flash over of Y-Phase Suspension Insulator string on LV side of ICT-1 near 220kV Bus-1 and there was a bird nest on the boom above this suspension insulator string.
Remedial Measures Taken: Replaced the flashed Y-Phase Suspension string insulators with new one, removed the bird nest and charged the 220kV Bus-1.
W.r.t. above, SRPC pointed out that TSTRANSCO should carry out periodic inspection and condition monitoring of switchyard equipment to ensure their proper working all the time.
As per the report submitted, triggering incident was failure of 4CX25 sq mm Copper Cable running from battery charger (in Tripping of 18 13-Nov-20 the control room) to DCDB panel 400/220 kV ICT-3 - - GI-2 15:02 hrs in Kiosk No.7. This resulted in DC at Hoody current leakage and CB opened. No load was affected as 500MVA ICT1 & ICT3 are in parallel. Tripping needs review.
Tripping of 400/220 kV ICT-3 at Hoody (KPTCL): As per FIR/ TR, 400/220 kV ICT-3 at Hoody tripped at 15:02 hr. due to the DC failure. On inspection, the 4CX25sqmm Copper Cable - main incomer 220kV side DC source-2 running from the battery charger (in the control room) to the DCDB panel in Kiosk No.7 (500Mtrs) was found faulty. The 4Cx25sqmm copper cable (main incomer 220kV side DC source-2) was isolated from the system. As a temporary measure, the source 1 & source-2 looped at the DCDB and both the sources made healthy.
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Annexure-B Deliberations: 400/220 kV ICT-3 at Hoody tripped at 15:02 hrs. due to the DC failure. KPTCL informed that the 4CX25 sqmm Copper Cable of main incomer 220kV side DC source-2 running from the battery charger (in the control room) to the DCDB panel in Kiosk No.7 (500 metre) was found faulty. The same was isolated and as a temporary measure, the source 1 & source-2 looped at the DCDB and both the sources made healthy.
As per the report submitted, 13-Nov-20 triggering incident was fault in 11:12 hrs 400kV KV Kota - Hinduja line-2. Tripping of 400kV Kalpakka - Gazuwaka line 19 400kV Kalpaka- tripped only at Gazuwaka end due - - GI-2 Gazuwaka Line-1 to suspected mal operation of 16-Nov-20 Main-2 (Schneider make P546 12:17 hrs type) SoTF function and the same needs review. Connectivity Diagram:
Trippings on 13-Nov-20 at 11:12 hrs:
Tripping of 400kV HNPCL- KV Kota line-2: HNPCL end: As per FIR/ DR/ EL/ TR line tripped in B-ph on B-E fault at 11:12:17.576 hrs on operation of DPR, Zone-1 (35.5km, 9.5kA), and attempted A/R but tripped in 3-ph due to persisting fault KV Kota end: As per FIR/ DR/ EL/ TR line tripped in B-ph on B-E fault at 11:12:17.663 hrs on operation of DPR, Zone-1 (177 km, 1.5kA), and attempted A/R but tripped in 3-ph due to persisting fault.
Tripping of 400kV Kalpakka Gazuwaka Line-1: Kalpaka (APTRANSCO) end: As per FIR, line was kept holding from Kalpaka end. Gazuwaka (PGCIL-SR1) end: As per FIR/ TR, line tripped at 11:12 hrs due to disturbance in 220 kV APTRANSCO Substation. As per DR, line tripped in B-ph at 11:06:24.535 hrs due to operation of DPR, Z1 (A/R) operation from Main-1 relay, and tried to auto-reclose after a dead-time of 1 sec. However, due to persistent nature of the fault, line tripped in 3-ph.
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Annexure-B As per EL, line tripped at 11:12:17 hrs due to DPR, Z1 (A/R) operation from Main-2 relay, and tried to auto-reclose after a dead-time of 1 sec. However, due to persistent nature of the fault, line tripped in 3-ph. In EL, SOTF operation from Main-1 relay & its RESET were also observed around this time (12:17 hrs) at A/R initiation. In EL, (msec) are not visible. Time sync issue in DR.
Trippings on 16-Nov-20 at 12:17 hrs:
Tripping of 400kV HNPCL- KV Kota line-2: HNPCL end: As per FIR/ DR/ EL/ TR line tripped in B-ph on B-E fault at 12:17:07.432 hr. on operation of DPR Zone- 1 and attempted A/R but tripped in 3-ph due to persisting fault (20.7km, 10.2kA). KV Kota end: As per FIR/ DR/ EL/ TR line tripped in B-ph on B-E fault at 12:17:07.419hr. on operation of DPR Zone- 1 and attempted A/R but tripped in 3-ph due to persisting fault (178 km, 1.57kA).
Tripping of 400kV Kalpakka Gazuwaka Line-1: Kalpaka (APTRANSCO ) end: As per FIR line did not trip at Kalpaka end. It was stated by APTRANSCO in FIR that the relays are operating only at Gazuwaka(PGCIL) end, whenever any fault occurs in 400KV KV Kota-HNPCL lines. Gazuwaka (PGCIL-SR1) end: As per FIR/ TR, line tripped due to disturbance in 220 kV APTRANSCO Substation. As per DR/ EL, line tripped at 12:17:08.407 hr. due to operation of DPR Zone-1 (Main-2 relay only). As per DR, line tripped in B-ph at 12:17:07.407 hrs due to operation of DPR, Z1 (A/R) operation from Main-1 relay, and tried to auto-reclose after a dead-time of 1 sec. However, due to persistent nature of the fault, line tripped in 3-ph. As per EL, line tripped at 12:17 hrs due to DPR, Z1 (A/R) operation from Main-2 relay, and tried to auto-reclose after a dead-time of 1 sec. However, due to persistent nature of the fault, line tripped in 3-ph. In EL, SOTF operation from Main-1 relay & its RESET were also observed around this time (12:17 hrs) at A/R initiation. In EL, (sec, msec) are not visible.
It was observed that SOTF initiation was from Main-I relay, not Main-II relay.
Deliberations: It was noted that on both the instances, 400kV KV Kota – HNPCL line tripped at both ends in B-ph on B-E fault due to operation of DPR Zone-1 and attempted A/R but tripped in 3-ph due to persisting fault. At the same time, 400kV Kalpakka - Gazuwaka Line-1 tripped at Gazuwaka end only on operation of DPR Zone-1 (Main -2 relay only).
PGCIL-SR1 informed that the line tripped due to configuration/setting issue in Main-2 relay (MiCOM- P546) at Gazuwaka SS. Line & Protection belongs to M/s APTRANSCO.
APTRANSCO informed that the line tripped on operation of SOTF function and CB close command was present during the tripping incident (during inspection CB close command/SOTF initiation was low). The presence of SOTF initiation to the Main-2 distance relay during fault occurrence was spurious and unwarranted. It was requested to M/s. PGCIL to plan for LC on 400 kV Kalpaka- Gajuwaka line-1 for thorough verification of the scheme of SOTF and to configure SOTF initiation & SOTF trip signals of main-2 relay in DR and also an alarm event to standby event logger of HMI PCs.
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Annexure-B APTRANSCO also informed that the matter was referred to M/s. Schneider (who commissioned these relays at 400KV PGCIL SS) for verification and confirmation of healthiness of scheme configuration to avoid mal operations.
Recommendations: APTRANSCO in coordination with PGCIL-SR-1 to resolve the spurious tripping of 400kV Kalpakka - Gazuwaka Line-1 on SOTF protection during the tripping of 400kV HNPCL- KV Kota line-2 including replacing the concerned line protection replays, P546. APTRANSCO to maintain proper ROW for 400kV HNPCL- KV Kota lines to avoid frequent faults on the line.
Triggering incident was failure of CB of U#5 at Srisailam RB. LBB Tripping of 220 kV operated resulting in the tripping Bus-1 at Srisailam 16-Nov-20 20 of all the elements connected to NIL NIL GI-1 Right Bank of 20:26 hrs Bus-1 at Srisailam RB. There was APGENCO no generation at Srisailam LB during antecedent conditions. SLD:
Bus configuration & arrangement: Bus- I: Generator U-5, Srisailam RB – Dindi line-1 Bus-II: Srisailam RB – Nagarjunasagar_TS line1
Tripping of 220kV Srisailam RB – Dindi line-1: Srisailam RB (APGENCO) end: As per FIR/ DR/ EL/ TR line tripped at 20:26:27.391 hr. on operation of LBB protection. As per TR, LBB protection of 220kV Bus-I operated due to Generator Unit-5 Circuit breaker failure and all Bus-I connected feeders were tripped.
Dindi (TSTRANSCO) end: As per FIR, line was in service at Dindi end.
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Annexure-B Tripping of 220kV Srisailam RB – Nagarjunasagar_TS line-1: Srisailam RB (APGENCO) end: As per FIR/ TR line, did not trip at Srisailam RB end. APGENCO informed that the line was connected to 220kV Bus2. Nagarjunasagar_TS (TSGENCO) end: As per FIR/ TR line tripped at 20:30 hrs on operation of earth fault protection. As per DR/ EL line tripped at 20:30:11.900 hr. Protection operated is not clear in DR/ EL. Only DEF pick up observed in DR. Time sync
Deliberations: TSGENCO informed that the triggering incidence for the events was Generator Unit-5 R-ph circuit breaker failure at 220kV Srisailam RB GS. This resulted in LBB operation of Unit-5 and it tripped all Bus-I connected elements including 220kV Srisailam RB – Dindi line-1, since unit-5 was connected to Bus-I. At the same time, 220kV Srisailam RB – Nagarjunasagar_TS line 1 (which was connected to Bus-II at Srisailam_RB was tripped at Nagarjunasagar_TS end only on operation of earth fault protection. TSGENCO was recommended to submit a report regarding tripping of this line. To this SRPC pointed out the following: that the mere opening of R-ph limb (due to failure/ blast) would not result in LBB unless there was also an occurrence of simultaneous fault. Without any fault, the opening of of R-ph limb of the said CB should result in operation of Pole Disrepancy relay, and should have opened the other two phase limbs of the CB. As such tripping of all 220 kV Bus-I connected elements needs review. Tripping of 220kV Srisailam RB – Nagarjunasagar_TS line from Nagarjunasagar_TS end on DEF operation was also not in order (the settings of DEF protection need to be revised appropriately).
Recommendations: TSGENCO to submit a report detailing the following, along with remedial action taken: LBB operation on account of the failure of R-ph limb of CB of Unit-5 and consequent tripping of all 220 kV Bus-I connected elements Tripping of 220kV Srisailam RB – Nagarjunasagar_TS line from Nagarjunasagar_TS end during above incident.
Tripping of As reported 400/230kV ICT-2 at 17-Nov-20 21 400/230 kV ICT-2 Pugalur tripped on operation of - - GI-2 17:27 hrs at Pugalur Buchholtz relay. Tripping of 400/230 kV ICT-2 at Pugalur (PGCIL-SR-2): As per FIR/ DR/ EL/ TR 400/230 kV ICT-2 at Pugalur tripped at 17:26:58.610 hr. on operation of Buchholz protection.
Deliberations: 400/230 kV ICT-2 at Pugalur tripped at 17:26:58.610 hr. on operation of Buchholz protection operation. PGCIL-SR2 informed that at the same time there was fault in downstream 230kV line (fault current of 14kA was fed by 230kV Pugalur bus). Transformer oil sample (1st) was tested, minor increment in gas parameters observed. Transformer kept under observation. 2nd sample of transformer oil was also tested; however much further increment was not noticed. PGCIL –SR2 informed that one more sample would be tested to ascertain healthiness of the transformer.
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Annexure-B Suspected tripping of 400/230 kV ICT-1 and 2 at Madurai due to Tripping of testing of 230kV BBP scheme. 400/230 kV ICT-1 However, as per the information 17-Nov-20 22 and 2 at 400/230 furnished by TANTRANSCO, leads - - GI-2 16:23 hrs kV Checknaurani of all bays were disconnected prior SS to testing. Hence there is no possibility to extend the trip signal. Tripping needs review. Tripping of 400/230 kV ICT-1 and 2 at 400/230 kV Checknaurani SS (TANTRANSCO): As per FIR/ DR/ EL/ TR, 400/230 kV ICT-1 & ICT-2 tripped on 230 kV side at 16:23:43.076 hr. due to BBP operation of 230kV Bus of TANTRANSCO. But in DR& EL of ICT relay, BBP Operation of 230 kV Bus was recorded.
Deliberation: SRLDC informed that 400/230 kV ICT-1 and 2 tripped due to BBP operation during testing of 230kV BBP scheme at 230kV Checkanuarani TANTRANSCO end. However, TANTRANSCO informed that leads of all bays were disconnected prior to testing; as such, there was no possibility of extending the trip signal. They suspect possibility of some DC mixing that might have caused BBP trip and led to tripping of ICTs. PGCIL SR-2 stated that trip signal was received directly at breaker. SRPC asked TANTRANSCO and PGCIL-SR2 to furnish report regarding tripping of the ICTs.
Triggering incident was BE fault in 230kV Trichy TN - Alandur line-1. Tripping of 230 kV Due to non-opening of breaker at Bus-1 at 230/ 110 17-Nov-20 230kV Trichy TN end, LBB 23 NIL NIL GI-1 kV Trichy-TN SS of 00:01 hrs operated resulting in the tripping TANTRANSCO of all the elements connected to 230 kV Bus-1 at 230kV Trichy TN SS. Connectivity Diagram:
Bus configuration and arrangement at 230kV Trichy SS: Single Bus arrangement
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Annexure-B SLD:
Tripping of 230kV Bus at Trichy TN SS of TANTRANSCO: As per DR/ EL/ TR, all elements connected to 230kV Bus at Trichy SS tripped at 00:01:16.277 hr. on operation of LBB protection.
Deliberations: In the antecedent conditions, 230kV Trichy SS was operating on single Bus. Triggering incidence for the event was B-E fault on 230kV Trichy TN - Alandur line-1. The fault was detected in Zone-1 at Trichy end, but the feeder did not clear the fault. This led to LBB operation of the 230kV bus, tripping all connected elements. TANTRANSCO informed that the defective breaker was subsequently isolated. SRPC asked TANTRANSCO to provide multi-bus operation at their 230 kV Trichy SS. Remedial action taken: TANTRANSCO informed that 230 kV Alundur – 1 CB was taken under LC on 17.11.2020 and mechanism /overhauling work was in progress.
Recommendations: TANTRANSCO to take steps to provide multi-bus operation at their 230 kV Trichy SS.
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Annexure-B As per the report submitted, DT was received at Vemagiri end and Tripping of 400 kV 21-Nov-20 line tripped only at this end. At 24 Vemagiri - GMR - - GI-2 11:34 hrs GMR end because of maloperation line-2 of Main-1 relay DT was sent and line was holding at this end. Tripping of 400 kV Vemagiri - GMR line-2: GMR end: No Tripping Files furnished.
Vemagiri (APTRANSCO) end: As per FIR/TR, line tripped at 11:34 hr. on receipt of DT from remote end. APTRANSCO informed that at Vemagiri end, DR events in Main-1 and Main-2 relays (ABB make, REL 521 and REL 316) of that tripping got over-written due to continuous receipt of carrier signal.
Deliberations: 400 kV Vemagiri - GMR line-2 tripped at Vemagiri end on receipt of DT. APTRANSCO informed that Main-1 relay at GMR end had mal-operated and sent spurious DT to Vemagiri end. The mal-operated Main-1 relay at GMR end was replaced. APTRANSCO also informed that the existing Main-1 and Main-2 relays at Vemagiri end would be replaced soon with SIFANG make CSC 103 and ABB make RED 670 under PSDF scheme.
Remedial Measures Taken: APTRANSCO informed that Main-1 relay at GMR end had mal-operated and sent spurious DT to Vemagiri end. The mal-operated Main-1 relay at GMR end was replaced.
As per the report submitted, triggering incident was DC earth Tripping of leakage in the cable connected 26-Nov-20 25 400kV/220kV from DC Distribution board to - - GI-2 16:02 hrs Julurupadu-ICT-1 Transformer. Because of this LV side CB tripped. Tripping needs review. Tripping of 400kV/220kV Julurupadu-ICT-1: As per FIR/ EL, 400kV/220kV ICT-1 at Julurupadu tripped at 16:01:58.581 hr. due to DC earth leakage in the cable from DC distribution board to Transformer Kiosk.
Deliberations: 400kV/220kV ICT-1 at Julurupadu tripped at 16:01:58.581 hr. due to DC earth leakage in the cable from DC distribution board to Transformer Kiosk. TSTRANSCO informed that the damaged cable was replaced and ICT charged.
Remedial Measures Taken: TSTRANSCO informed that the damaged cable, which caused DC earth leakage, had been replaced and ICT charged.
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Annexure-B Triggering incident was failure of R-ph CB of 220kV Shanakarapalli - Tripping of 220kV Parigi line-1 at Shanakarapalli end. Bus-2 at 400/ 220 26-Nov-20 26 LBB operated resulting in the NIL NIL GI-1 kV Shankarapalli SS 07:57 hrs tripping of all the elements of TSTRANSCO connected to Bus-2 at Shankarapalli SS. Connectivity Diagram:
Bus configuration and arrangement: Double Main and transfer bus arrangement
Tripping of 400/ 220kV, 315 MVA ICT-2 at Shankarapalli (TSTRANSCO) end: As per FIR/ TR, ICT-2 tripped at 07:57 hrs on operation of 220kV Busbar Zone-2 protection for a fault on 220kv Shankerpally-Parigi feeder-1. Breaker problem at 220kv Shankerpally end on 220 kV Parigi feeder-1 was suspected. As per EL, ICT-2 tripped at 07:57:38.612 hrs on operation of BB protection. As per DR, ICT-2 tripped at 02:27:38.917hrs on operation of LBB protection. (DR in PDF format not furnished). Time sync difference between DR and EL.
Tripping of 400/ 220kV, 315 MVA ICT-4 at Shankarapalli (TSTRANSCO) end: As per FIR/ DR/ EL/ TR, 400/ 220kV 315 MVA ICT-4 tripped at 07:57:38.495 hrs on operation of LBB protection.
Deliberations: The triggering incidence for the events was R-E fault on 220kV Shankarapalli – Parigi line -1. TSTRANSCO informed that breaker problem of the line (non-opening of R-ph limb) resulted in LBB operation of Bus-2 and tripped all Bus-2 connected elements, including 400/ 220kV, 315 MVA ICT-2 & 4. The damaged limb was replaced on 14 Dec 2020.
Remedial Measures Taken: TSTRANSCO informed that the damaged R-ph limb of 220kV Shankarapalli – Parigi line -1 was replaced on 14 Dec 2020.
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Annexure-B As per the report submitted, triggering incident was receipt of Tripping of 400 kV 28-Nov-20 DT signal at Dindi end, because of 27 Srisailam LB - Dindi - - GI-2 17:21 hrs Relay mal-operation at Srisailam line-1 end. Line tripped only at Dindi end. Tripping of 400 kV Srisailam LB - Dindi line-1: Srisailam LB (TSGENCO) end: As per FIR, line was kept holding from Srisailam LB end. Dindi (TSTRANSCO) end: As per FIR/ DR/ EL, line tripped at 16:43:43.679 hr. on receipt of DT signal. As per DR, Trip Bus-1 OP signal was also observed at the same time.
Deliberations: 400kV Srisailam – Dindi line -1 tripped at Dindi end only on receipt of DT signal. TSGENCO informed that DT was transmitted from Srisailam end, but there was no event record in relay. TSTRANSCO informed that PLCC end-to-end testing was carried out in November but no abnormality was detected. PCSC forum suggested that DC earth mat resistance at Srisailam LB shall be checked for DC leakage, if any.
Units 1,3,4 and 5 at Jindal TPS (780 MW) tripped due to flash over in GIS Chamber and Units#1 and 2 at Multiple Trippings BTPS (906 MW) tripped due to at 400kV Jindal TPS 29-Nov-20 electrical side problem. Complete 28 of JSWEL and 1690 NIL GI-2 13:16 hrs Generation loss of 1690 MW. 400kV BTPS of 400kV Jindal – BTPS line, 400kV KPCL Jindal – BPS line-1, and 400kV BTPS – Hiriyur line-1 also tripped during this event. SLD of JSWEL:
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Annexure-B Bus configuration and arrangement at 400kV JSWEL GIS SS: Double Bus with bus coupler
Connectivity diagram:
Tripping of 400kV JSWEL – BTPS line: JSWEL end: As per FIR/ TR, line was kept holding, and was later hand-tripped. As per DR/ EL, the fault was sensed in Zone-4 at JSWEL end. BTPS (KPCL) end: As per FIR/ DR/ EL/ TR line tripped on R-E fault at 13:15:15.218 hr. on operation of DPR Zone-2 after Zone-2-time delay of 350msec (10.9kA, 19.05km). Time sync
Tripping of 400kV JSWEL – BPS line-1: JSWEL end: As per FIR/ TR line did not trip at JSWEL end and was hand-tripped. BPS (KPTCL) end: As per FIR/ DR/ EL/ TR line tripped on R-E fault at 13:16:31.423 hr. on operation of DPR Zone-2 after Zone-2-time delay of 350msec (8.6kA, 12.7km).
Tripping of 400kV BTPS-Hiriyur line-1: Hiriyur (PGCIL-SR2) end: As per FIR/ TR line did not trip at Hiriyur end. BTPS (KPCL) end: As per FIR/ TR line tripped at 13:16 hr. due to operation of DPR Zone-4. As per FIR Unit-1 and Unit-2 also tripped at the same time.
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Annexure-B Deliberations: Triggering incidence was R-E fault in 400kV bus at JSWEL GIS SS. 400kV JSWEL - BPS line-1 and 400kV JSWEL – BTPS line tripped at remote end on operation of DPR Zone-2 and did not trip at JSWEL end. At the same time, 400kV BTPS-Hiriyur line-1 also tripped at BTPS end due to DPR Zone-4 operation. Further, Gen Unit-1 and Gen Unit-2 also got tripped during the incident. JSWEL informed that 220 KV Line-1 and Line-2 and 220KV Bus coupler opened on Islanding scheme, which was triggered to operate on sensing of loss of voltage. JSWEL also informed that Generating Unit-1 and CPP Units -3 and 4 tripped on standby earth fault. To this, SRPC emphasized that formation of any local island at any generation must occur sufficiently below the regional islanding frequency of southern grid, which is 47.9 Hz, and asked JSWEL to ensure this. Remedial action taken by JSWEL: JSWEL informed that the R-E fault was within BBP Zone at JSWEL end but as the R-ph BBP relay was faulty (the relay was in ready mode), Busbar protection did not operate. I/O module in BBP was faulty and the same was replaced. W.r.t. tripping of 400 kV BTPS-Hiriyur line during above instance, SRPC pointed out that the tripping was not in order, and asked KPCL to check time setting of Reverse Zone (Z4) adopted at BTPS end, and to revise it suitably to 0.5 sec. W.r.t. tripping of GU-1 & GU-2 at BTPS, KPCL informed that tripping of GU-1 at BTPS was due to tripping of ID fans on detection of voltage dip. Unit-2 tripped due to turbine trip. On this, SRPC pointed out that in order to avoid tripping of Units on voltage dip, it had been recommended to provide a suitable time delay of 100 msec for ID fans tripping on detection of voltage dip. PCSC forum also requested KPCL to furnish a report regarding tripping of GU-2 on turbine protection trip at their BTPS during Bus fault at JSWEL GS.
Recommendations: KPCL to furnish a report regarding tripping of Generating Unit-2 on turbine protection trip at their BTPS station during Bus fault at JSWEL GS. KPCL to check & revise Reverse Zone (Z4) settings adopted on all 400 kV lines rmanating from their BTPS station. KPCL to provide appropriate time delay of say, 100 msec for ID fans tripping on detection of voltage dip.
As per the report submitted, triggering incident was PT fuse 01-Dec-20 failure at N'sagar end. Line tripped 15:45 hrs only at N'sagar end and was
holding at Tallapally end
As per the report submitted,
triggering incident was R-E fault in
03-Dec-20 the line. Line tripped only at
21:30 hrs N'sagar end because of suspected
maloperation of DEF protection.
Tripping needs review.
29 Tripping of 220kV- As per the report submitted,
Talapally - triggering incident was R-E fault in
Nagarjunasagar_TS 06-Dec-20 the line. Line tripped only at
line-3 20:00 hrs N'sagar end because of suspected
maloperation of DEF protection - - GI-1 and the same needs review. 20-Dec-20 As per the report submitted, 21:25 hrs triggering incident was R-E fault in
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Annexure-B the line. At N’sagar end, DEF operated and line tripped only at this end. Line was holding at Tallapally end. Tripping needs review. As per the report submitted, triggering incident was R-E fault in the line.DEF operated at N’sagar 23-Dec-20 end and the line tripped only at 00:16 hrs this end. Line was holding at Tallapally end. Tripping needs review.
1. Tripping 01-Dec-20 at 15:45 hrs: Talapally (APTRANSCO) end: As per FIR line did not trip at Talapally end. Nagarjunasagar_TS (TSGENCO) end: As per FIR/ EL line tripped at 03:34:02.551 hr. on PT fuse failure.
Deliberations: As per tripping files furnished, 220kV-Talapally -Nagarjunasagar_TS line-3 tripped at N’Sagar end only on PT fuse failure. TSGENCO informed that PT fuse had blown off and the same was replaced.
2. Tripping on 03-Dec-20 at 21:30 hrs: Talapally (APTRANSCO) end: As per FIR line did not trip at Talapally end. Nagarjunasagar_TS (TSGENCO) end: As per FIR/ DR/ EL/ TR line tripped on R-E fault at 21:20:58.615 hr. on operation of earth fault protection. Earth fault protection trip to be configured in DR and EL. Time sync difference between DR and EL.
3. Tripping on 06-Dec-20 at 20:00 hrs: Talapally (APTRANSCO) end: As per FIR line did not trip at Talapally end. Nagarjunasagar_TS (TSGENCO) end: As per FIR/ DR/ EL/ TR line tripped on R-E fault at 20:00:56.361 hr. on operation of earth fault protection (3.4kA). Earth fault protection trip to be configured in DR and EL. Time sync difference between DR and EL.
4. Tripping on 20-Dec-20 at 21:25 hrs: Talapally (APTRANSCO) end: As per FIR line did not trip at Talapally end. Nagarjunasagar_TS (TSGENCO) end: As per FIR/ DR/ EL/ TR line tripped on R-E fault at 21:25:27.237 hr. on operation of earth fault protection (486A). Earth fault protection trip to be configured in DR and EL. Time sync difference between DR and EL.
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Annexure-B 5. Tripping on 23-Dec-20 at 00:16 hrs: Talapally (APTRANSCO) end: As per FIR line did not trip at Talapally end. Nagarjunasagar_TS (TSGENCO) end: As per FIR/ DR/ EL/ TR line tripped on R-E fault at 12:16:17.139 hr. on operation of earth fault protection (486A). Earth fault protection trip to be configured in DR and EL. Time sync difference between DR and EL.
Deliberations: W.r.t. first tripping on VT fuse failure, SRPC asked TSGENCO to ensure the following: “Under VT fuse fail conditions, DPR operation should be kept blocked. In case of a fault under those conditions, the internal Over Current element of the DPR should become active to provide protection to the subject line.” W.r.t. Trippings 2 to 5, it was noted that 220kV Talapally -Nagarjunasagar_TS line tripped at Nagarjunasagar_TS end only on R-E fault on operation of earth fault protection. TSGENCO informed that it was due to DEF relay mal-operation. Whenever the relay senses small disturbance, DEF trip was getting extended without any time delay. Remedial action: TSGENCO also informed that the problem was rectified on 26th December 2020. Presently the DEF relay was extending only DEF initiation for any disturbance, and trip would be extended only after time delay as per the curve.
As per the report submitted, triggering incident was Y-E fault in 400kV Gajwel-Narsapur line -1. Fault was sensed in zone-1 protection at Narsapur end and Multiple Trippings carrier aided Zone-2 protection 02-Dec-20 30 in 400kV Gajwel SS operated at Gajwel end. A/R - - GI-2 03:07 hrs of TSTRANSCO operated and successful at both the ends. At the same time, 400KV Gajwel-Chandulapur-2 line tripped at Gajwel end only on suspected maloperation of SOTF and the same needs review. Tripping of 400kV Gajwel-Narsapur line-1: Gajwel (TSTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped in Y-ph on Y-E fault at 03:03:27.906 hrs on operation of DPR, Zone-2 CAT and auto-reclosed successfully. Narsapur (TSTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped in Y-ph on Y-E fault at 03:04:27.793 hrs on operation of DPR, Zone-1 and auto-reclosed successfully. Time sync issue between both ends.
Tripping of 400kV Gajwel-Chandulapur line-2: Chadulapur (TSTRANSCO) end: As per FIR, line was holding at Chandulapur end. Gajwel (TSTRANSCO) end: As per FIR/ DR/ EL, line tripped at 03:03:27.926 hrs on SOTF operation during fault on 400kV Gajwel- Narsapur line. TSTRANSCO informed that the same would be checked by availing LC.
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Annexure-B Deliberations: Triggering incidence for the event was Y-E fault on 400kV Gajwel- Narsapur line. The line tripped in Y-ph on operation of DPR Zone-1 at Narsapur end and DPR Zone-2 CAT at Gajwel end, and autoreclosed successfully. At the same time 400kV Gajwel-Chandulapur line-2 also tripped at Gajwel end only on operation of SOTF protection. TSTRANSCO informed that SOTF protection of REL670 relay at Gajwel was taking voltage and current as inputs. Hence on detection of dip in voltage due to fault in neighbouring lines, SOTF protection operated. PCSC forum suggested that SOTF protection at Gajwel should take breaker status as input and only during change in breaker status from Open to close, it would sense current and operate in case of fault.
Recommendations: TSTRANSCO to modify SOTF logic at Gajwel and ensure that SOTF protection takes breaker status as input and only during change in breaker status from Open to close, it would sense current and operate in case of fault.
As per the report submitted, 400kV/220kV ICT#1 at Dichipalli Tripping of tripped on operation of 04-Dec-20 31 400/220 kV ICT-1 Differential protection due to - - GI-2 15:42 hrs at Dichipally SS testing of Tie CT (same dia) wiring by MRT wing. Tripping needs review. Tripping of 400/220 kV ICT-1 at Dichpally (TSTRANSCO): As per FIR/ DR/ EL, 400/ 220kV ICT-1 tripped at 15:40:20.121 hr. on operation of differential protection. TSTRANSCO informed that ICT-1 tripped while MRT wing was testing wiring of Tie CTs of same Dia and instructed MRT Wing to take proper precautions while testing.
Deliberations: 400/ 220kV ICT-1 tripped on operation of differential protection. TSTRANSCO informed that ICT-1 tripped while MRT wing was testing wiring of Tie CTs of the same Dia, without proper isolation. TSTRANSCO stated that MRT Wing was instructed to take proper precautions while testing. PCSC forum recommended TSTRANSCO to follow proper protocols while testing.
As per the report submitted, triggering incident was 3-ph fault in the line at a distance of 3.4kM from Sabarigiri end. At Sabarigiri end, Zone-1 distance protection Multiple Trippings 04-Dec-20 operated and resulted in 3 phase 32 at 220kV Sabarigiri - - GI-1 18:10 hrs trip. At Theni end, Zone-2 distance GS protection operated and resulted in 3 phase trip. Non operation on carrier aided protection needs review. Tripping of unit -5 needs review.
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Annexure-B Connectivity diagram:
Bus configuration and arrangement: Double Bus with Bus coupler (closed)
Tripping of 220kV Sabarigiri – Theni line: Sabarigiri (KSEBL) end: As per FIR/ TR line tripped on 3-ph fault at 18:10 hr. on operation of distance protection Zone-1 (3.3km, Ir-9.39kA, Iy-10.18kA, Ib-10.34kA) As per DR/ EL, line tripped at 18:10:12.608 hr. on operation of Relay definitive trip. As per FIR Sabarigiri Unit-5, 66kV Sabarigiri – Kochupampa line also tripped at the same time. Carrier sent, Zone pick up and Trip to be clearly configured in DR/ EL. Time sync issue
Theni (TANTRANSCO) end: As per FIR/ DR/ EL/ TR line tripped on 3-ph fault at 18:10:44.685 hr. on operation of DPR Zone-2. (110.6km, Td~ 350msec) Grid Occurrences discussed in the 94th Meeting of PCSC held on 29th January 2021 72/87
Annexure-B Deliberations: 220kV Sabarigiri – Theni line tripped on 3-ph fault due to operation of DPR Zone-1 at Sabarigiri end and Zone-2 at Theni end. KSEBL informed that non-operation of carrier aided protection of 220kV Sabarigiri-Theni feeders was due to the terminal connection issue in the PLCC panel at Theni end. Along with 220kV Sabarigiri – Theni line, 66kV Kochupamba feeder also tripped with R- phase to earth indication. KSEBL informed that both 220kV Sabarigiri – Theni feeder and 66kV Kochu Pamba feeder are passing through the same area for some distance. Heavy lightning was prevailing in the area at the time of the event. Both feeders tripped as a consequence of lightning. Unit No. 5 at Sabarigiri GS also tripped simultaneously on non-lock out with cooling water flow low indication, and had gone to turbine operation (spinning) mode. KSEBL informed that the tripping was due to auxiliary supply failure of the unit consequent to voltage dip.
Remedial Measures Taken: KSEBL informed vide report dated 23.01.2020 the following RM: Steps have been initiated to provide distance relay for 66kV Kochu Pamba feeder. The logic scheme of Unit#5 would be modified to prevent unwanted tripping during momentary loss of cooling water flow. No issues were found on the-LT supply scheme of Unit-5 auxiliary. Carrier aided protection issue was verified and corrected on 26.12.2020.
Tripping of As per the report submitted, 400KV/110kV 07-Dec-20 triggering incident was operation 33 - - GI-2 Thennampatty-ICT 03:56 hrs of PRV-2 trip protection due to - 3 heavy rain. Tripping needs review. Tripping of 400KV/110kV Thennampatty-ICT – 3: As per FIR/ DR/ EL/ TR, 400KV/110kV ICT-3 tripped at 03:56:02.896 hr. on PRV-2 trip. TANTRANSCO informed that PRV-2 protection operated due to moisture inside the PRV-2 relay due to heavy rains.
Remedial Measures Taken: TANTRANSCO informed that both PRV – 1 & 2 have been covered suitably.
Triggering incident was Yph Bus Tripping of 400kV Coupler CT failure at 400kV NLC Bus-1 and Bus-2 at TS-2. 400kV Bus-1 and Bus-2 BBP 07-Dec-20 34 400kV/230kV NLC operated resulting in the tripping 300 NIL GI-2 18:59 hrs TS-2 Generating of all the connected elements. Station 230kV bus was intact during this event. Bus configuration and arrangement: Double Main and transfer Bus
Bus -1 400kV Neyveli TS-II – Nagapattinam line, 400kV Neyveli TS-II – Salem line-1, 400kV Neyveli TS-II – Neyveli-TS-II (Exp), 400/ 220kV ICT-2 Bus -2 400kV Neyveli TS-II – Pugalur line, 400kV Neyveli TS-II – Salem line-2, 400kV Neyveli TS-II – Neyveli-TS-I (Exp), 400kV Neyveli TS-II – NNTP line, 400/ 220kV ICT- 1
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Annexure-B SLD:
Tripping of 400kV Neyveli TS-II – Nagapattinam line: Neyveli TS-II (NLCIL) end: As per FIR/ DR/ TR, line tripped on 3-ph fault at 19:00:45.553 hrs on operation of BBP of Bus-1 & Bus- 2 and DT was sent to remote end. As per EL line tripped at 19:00:45.532 hr.
Nagapattinam (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped at 19:00:46.571 hr. on receipt of DT from remote end.
Tripping of 400kV Neyveli TS-II – Pugalur line: Neyveli TS-II (NLCIL) end: As per FIR/ DR/ TR line tripped at 18:59 hrs on operation of BBP of Bus-1 & Bus-2. As per DR/ EL line tripped at 18:59:25.202 hr. Protection operated not configured in DR or EL.
Pugalur (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped at 18:59:26.156 hrs on receipt of DT from remote end.
Tripping of 400kV Neyveli TS-II – Salem line-1: Neyveli TS-II (NLCIL) end: As per FIR/ DR/ TR line tripped at 19:00:45.586 hr. on operation of BBP of Bus-1 & Bus-2.
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Annexure-B As per EL line tripped at 19:00:42.538 hr. Time sync between DR and EL. Salem (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped at 19:00:46.670 hr. on receipt of DT from remote end.
Tripping of 400kV Neyveli TS-II – Salem line-2: Neyveli TS-II (NLCIL) end: As per FIR/ DR/ EL TR line tripped at 18:59:25.169 hr. on operation of BBP of Bus-1 & Bus-2. Salem (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped at 18:59:26.190 hr. on receipt of DT from remote end.
Tripping of 400kV Neyveli TS-II – Neyveli-TS-II (Exp): Neyveli TS-II (NLCIL) end: As per FIR/ TR line tripped at 18:59hr. on operation of BBP of Bus-1 & Bus-2. As per DR line tripped at 19:00:45.497 hr. As per EL line tripped at 18:59:25.175 hr. (BC 96 OPTD) Protection on which line tripped not configured in DR/ EL. Neyveli-TS-II (Exp) end: No tripping files (FIR/DR/EL/TR) uploaded.
Tripping of 400kV Neyveli TS-II – Neyveli-TS-I (Exp): Neyveli TS-II (NLCIL) end: As per FIR/ DR/ EL/ TR line tripped at 18:59:26.209 hr. on operation of BBP of Bus-1 & Bus-2. Neyveli-TS-I (Exp) end: No tripping files (FIR/DR/EL/TR) uploaded.
Tripping of 400kV Neyveli TS-II – NNTP line: Neyveli TS-II (NLCIL) end: As per FIR/ DR/ EL/ TR line tripped on R-Y-E fault at 13:29:28.144 hr. (EL) on operation of differential protection. Time sync of EL NNTP end: As per FIR/ DR/ EL/ TR line tripped on R-Y-E fault at 18:59:26.209 hr. on operation of differential protection.
Tripping of 400/ 220kV ICT-1 & 2 at Neyveli TS-II (NLCIL) end: As per FIR/ DR/ EL/ TR 400/ 220kV ICT-1 at Neyveli TS-II tripped on R-Y fault at 18:59:26.162 hrs due to operation of HV side BBP operation. As per FIR/ EL/ TR 400/ 220kV ICT-2 at Neyveli TS-II tripped at 19:00:46.265 hrs due to operation of HV side BBP operation.
Deliberations: It was noted that no NLCIL representative had come to attend the meeting. As per the tripping files furnished, the triggering incidence for the events was 400kV Bus Transfer Bay Y-ph and B-ph CT failure (blast) and Y-ph Bus Transfer Breaker failure. This resulted in Bus fault on 400kV Neyveli TS-II Bus- I & II and operation of BBP of both buses tripping all 400kV elements connected to both buses. BBP also sent DT to remote end. It was also mentioned that Units- 4 & 7 got tripped during the incidence resulting in generation loss of nearly 300MW. PCSC forum recommended NLCIL to submit detailed report regarding tripping of 400kV Buses at NLC TS-2 GS clarifying the following: Grid Occurrences discussed in the 94th Meeting of PCSC held on 29th January 2021 75/87
Annexure-B (i) Exact location of the fault, nature of fault (ii) Status of Bus coupler during fault (iii) Whether BBP operated simultaneously for both buses, if not reason for the same and (iv) Remedial Measures Taken for the tripping.
Recommendations: NLCIL to submit a detailed report regarding tripping of 400kV Buses at NLC TS-2 GS clarifying the following: Exact location of the fault, nature of fault Status of Bus coupler during fault Whether BBP operated simultaneously for both buses, if not reason for the same and Remedial measures taken for the tripping.
Triggering incident was BE fault in 220kV Guttur - Jogihalli line. Due to non-opening of B-ph pole CB at 220kV Guttur end, LBB operated resulting in the tripping of all the Tripping of 220kV elements connected to Bus-1 at Bus-1 at 16-Dec-20 220kV Guttur SS. It may be noted 35 NIL NIL GI-1 400kV/220 kV 10:17 that all elements were connected Guttur SS of KPTCL to 220kV Bus-1 at Guttur SS during antecedent conditions due to CB replacement works. 400kV Guttur - Kaiga line-2 and 400kV/220kV ICT#1 at Kaiga also tripped during this event. Bus configuration and arrangement at 220kV: Single Bus operation
Antecedent conditions: Due to replacement work of Neelagunda line CB, all elements except Neelagunda were connected to 220kV Bus-1. Neelagunda line was charged through Bus Coupler CB.
Tripping of 220 kV Guttur – Jogihalli line: Guttur (KPTCL) end: As per KPTCL report line tripped on B-E fault due to operation of DPR Zone-1 (1.483kA, 5.206km) Subsequently LBB was initiated and tripped all elements connected to 220kV Bus. M2 Siemens relay has not sensed any fault. No such fault current records in 21M2 & the Bus Bar PU. Hence mal operation of external LBB function in M1 relay was suspected. Jogihalli end: No protection operated.
Tripping of 400/ 220kV ICT -1 & 2 at Guttur SS (KPTCL) end: As per FIR/ TR, ICT -1 & 2 tripped on LV side at 10:15 hrs on operation of LBB protection of 220kV Bus-1. KPTCL informed that all 220kV lines CB & 220kV side CB’s of ICT’s tripped due to LBB operation of 220 kV Wish wind line (B-E fault, Zone-1, 1.483kA, 5.02km). They also informed that only in M1 Areva-P437 distance relay fault triggered & LBB operated resulting in tripping of220 kV Bus Bar –I. No events triggered in M2 – P444 relay or Bus bar line PU.
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Annexure-B Tripping of 400kV Kaiga – Guttur line-2: Kaiga (NPCIL) end: As per FIR/ DR/ TR line tripped in 3-ph on B-E fault at 10:15:40.193 hr. on operation of DPR Zone-1 (3.352 kA, 67.88 Km) and attempted A/R but A/R locked. As per EL line tripped on B-E fault at 10:12:38.150 hr. on operation of DPR Zone-1 and attempted A/R. From DR/EL, A/R lockout was observed at the operation of DPR, Z1 protection. CB status to be configured in DR as well. Time sync between DR and EL Guttur (KPTCL) end: As per FIR/ DR/ TR line tripped in B-ph at 10:15:40.204 hr. on B-E fault due to DPR, Zone-2 (A/R, CAT, If-2.8kA, 151.2kms) operation. But within 60 msec into A/R progress, line tripped in 3-ph due to due to DT receipt from remote end.
Tripping of 400/ 220kV ICT -1 at Kaiga GS (NPCIL) end: As per FIR / EL/ TR, ICT-1 tripped at 10:12:38.137 hr. on operation of TEED protection. NPCIL informed that Guttur line-2 breaker CB-2B was kept open for maintenance. Guttur line-1 was out of service with its line isolator open at Kaiga end. Guttur-line-1 CB-1B was kept closed and breaker CB- 1C was kept open for CT-3 Maintenance. It was suspected that during tripping of Kaiga- Guttur-2, CT-3 primary circuit might have sensed the line current, possibly due to ground circulation current got induced in the line because of fault in Kaiga Guttur -Line 2, which in turn led to initiation of TEED Protections.
Deliberations: The triggering incidence for the events was B-E fault 400kV Kaiga – Guttur line-2. The line tripped on operation of DPR Zone-1 at Kaiga end Zone-2 CAT at Guttur end. A/R was attempted at both ends but locked out at Kaiga end due to operation of TEED protection of ICT. At Guttur end, A/R locked out due to DT receipt from remote end. 400/ 220kV ICT -1 at Kaiga GS tripped at the same time on TEED protection operation. NPCIL informed that Guttur line-2 breaker CB-2B was kept open for maintenance. Guttur line-1 was out of service with its line isolator open at Kaiga end. Guttur-line-1 B breaker was kept closed and breaker CB- 1C was kept open for CT-3 Maintenance. Primary of CT-3 were kept earthed for maintenance. It was suspected that during tripping of Kaiga- Guttur-2, CT-3 primary circuit sensed the line current possibly due to ground circulation current got induced in the line because of fault in Kaiga Guttur - Line 2, which in turn led to initiation of TEED Protections. Simultaneously, 220 kV Guttur – Jogihalli line tripped at Guttur due to operation of DPR Zone-1 (1.483kA, 5.206km). Subsequently, LBB was initiated and tripped all elements connected to 220kV Bus-1. KPTCL informed that there was no fault on the line, 21M1 Areva P437 distance Main1 relay had mal- operated and issued trip signal. In Main 1 relay external LBB had been enabled. 400/ 220 kV ICT -1 & 2 at Guttur SS also tripped on operation of LBB protection of 220kV Bus-1. KPTCL informed that it was due to LBB operation of 220kV Wish wind line. 21M1 Areva P437 distance relay of the line had sensed B-E fault and triggered LBB operation tripping all 220kV Bus-1 connected elements.
Remedial Measures Taken: KPTCL informed that: External CB Fail function enabled in Main-I relay of 220kV Jogihally bay was disabled. Detailed testing of Relays and bay equipment in 220kV Jogihally bay would be carried out by M/s. Wish Wind Ltd. on 03.02.2021 by availing shut down.
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Annexure-B Pole-1 of HVDC Talcher-Kolar tripped due to problem in valve cooling system at Talcher end. Tripping of HVDC ESOF was received at Kolar end. 635 Talcher-Kolar After the tripping of Pole-1, rise in MW Pole-1 and 20-Dec-20 36 400kV Kolar voltage was observed - (SPS Multiple trippings 21:25 hrs and all connected 400kV lines at opera at 400/220 kV Kolar except 400kV Kolar - Hoody tion) Kolar SS line-1 tripped on operation of OV St-1 protection at Kolar end and DT was received at remote ends. Antecedent condition: Pole 1 power – 773 MW; Pole 2 power – 774 MW HVDC System was running on balanced bipolar operation with 1650 MW reference power at Talcher and 1547 MW power received at Kolar. AC Bus Voltage was 426kV and frequency 50.0Hz at Kolar end. At Kolar HVAC station, all 400kV lines, 220kV lines, ICT-1, 2 & Bus reactor were also in service.
Tripping of HVDC Talcher Kolar Pole-1: Kolar (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, HVDC Talcher – Kolar Pole-1 tripped at 21:24:52.886 hr. on receipt of Emergency switch off sequence (ESOF) signal from Talcher end. PGCIL-SR2 informed that the trip command at Talcher, was initiated by the valve cooling system at Talcher end. Pole-2 had initiated the changeover to metallic return; however, the sequence had failed. Pole-2 remained in operation in ground return, this eventually resulted in the power in Pole-2 to get ramped down to 150MW. SPS TK-1 was generated at Kolar. Immediately following the Pole tripping, AC filter-1 & AC filter-3 bus had also tripped at Kolar station.
Tripping of various 400 kV lines on OVR, Stage-I protection:
434010 KOLAR 400.00 414037 NP KUNTA 400.00 T1 130.7 0 G 434010 KOLAR 400.00 434003 HOODY 400.00 B1 51.07 0 A 434010 KOLAR 400.00 434003 HOODY 400.00 B2 51.07 0 C 434010 KOLAR 400.00 434005 SOMANAHALLI 400.00 T1 97.39 0 E 434010 KOLAR 400.00 444006 HOSUR 400.00 T1 69 0 B 434010 KOLAR 400.00 444006 HOSUR 400.00 T2 69 0 D 153.1 434010 KOLAR 400.00 444024 TIRUVALAM-PG400.00 T1 0 H 9
1. Tripping of 400kV Kolar – Thiruvalam line: Kolar (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped at 21:25:03.688 hr. on operation of Overvoltage stage-1 protection. (251kV, 252kV, 250kV, Td ~ 5sec) Grading as per OVR SRPC 2018 – H – 109%, 5sec
Thiruvalam (PGCIL-SR-2) end: As per FIR/ DR/ EL/ TR line tripped at 21:25:03.226 hr. on receipt of DT.
2. Tripping of 400kV Kolar – NP Kunta line: Kolar (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped at 21:25:01.146 hr. on operation of Overvoltage stage-1
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Annexure-B protection. (Td ~ 6sec) Grading as per OVR SRPC 2018 – G – 109%, 6sec NP Kunta (PGCIL-SR1) end: As per FIR/ DR/ EL/ TR line tripped at 21:25:01.675 hr. on receipt of DT.
3. Tripping of 400kV Kolar – Hosur line -1: Kolar (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped at 21:25:24.789 hr. on operation of Overvoltage stage-1 protection. (Td ~ 9sec) Grading as per OVR SRPC 2018 – B – 111%, 9sec Hosur (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped at 21:25:25.335 hr. on receipt of DT.
4. Tripping of 400kV Kolar – Hosur line -2: Kolar (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped at 21:25:11.535 hr. on operation of Overvoltage stage-1 protection. (Td ~ 8sec) Grading as per OVR SRPC 2018 – D – 110%, 8sec Hosur (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR, line tripped at 21:25:11.593 hr. on receipt of DT.
5. Tripping of 400kV Kolar – Hoody line -2: Kolar (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped at 21:25:16.255 hr. on operation of Overvoltage stage-1 protection. (Td ~ 10sec) Grading as per OVR SRPC 2018 – C – 110%, 9sec Hoody (KPTCL) end: As per FIR/TR, line tripped at 21:25 hrs.
6. Tripping of 400kV Kolar – Somnahalli line: Kolar (PGCIL-SR2) end: As per FIR/ DR/ EL/ TR line tripped at 21:25:06.185 hr. on operation of Overvoltage stage-1 protection. (Td ~ 7sec) Grading as per OVR SRPC 2018 – E – 110%, 7sec Somnahalli (PGCIL-SR-2) end: As per FIR/ DR/ EL/ TR line tripped at 21:25:06.234 hr. on receipt of DT.
7. Tripping of 400kV Hoody – Devanahalli line -1: Hoody (KPTCL) end: As per FIR/ DR/ EL/ TR line tripped at 21:25 hr. on operation of Overvoltage stage-1 protection. Grading yet to be provided. OVR start and trip to be configured in DR and EL. Devanahalli (PGCIL-SR-2) end: As per FIR/ TR, line tripped at 21:25 hr. on receipt of DT. No DR/ EL
Deliberations: HVDC Talcher – Kolar Pole-1 tripped at 21:24:52.886 hr. on receipt of Emergency switch off sequence (ESOF) signal from Talcher end. PGCIL-SR2 informed that the trip command at Talcher, was initiated by the valve cooling system. Pole-2 had initiated the changeover to metallic return, however, the sequence had failed. Auto-
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Annexure-B sequence to metallic return mode failed due to failure of associated VFD. Pole-2 remained in operation in ground return, this eventually resulted in the power in Pole-2 to get ramped down to 150MW. Consequently, SPS TK-1 was generated at Kolar. Immediately, following the Pole-1 tripping, AC filter-1 & AC filter-3 bus had also tripped at Kolar station. Subsequent to tripping of Pole-1 and AC filter banks, voltage of 400kV Kolar AC bus raised and resulted in tripping of 400kV Kolar – Thiruvalam line, 400kV Kolar – NP Kunta, 400kV Kolar – Somanahalli line, 400kV Kolar – Hosur lines – 1 & 2, 400kV Kolar – Hoody line-2. All these lines tripped on operation of overvoltage protection at Kolar end and DT receipt at remote end. 400kV Hoody – Devanahalli line-2 also tripped on overvoltage protection at Hoody end and DT receipt at Devanahalli end. SRPC pointed out that in antecedent conditions itself, voltage was high at Kolar (426kV), in spite of 63MVAR bus reactor in service. PGCIL-SR2 informed that CTU has been informed regarding requirement of more MVAR compensation at Kolar. In this regard, SRPC requested STLDC also to look into the issue, and provide suitable suggestions. SRLDC pointed out that during SPS TK-1 operation, total load relief obtained was only 635MW against designed value of 836MW. Load relief obtained from Karnataka and Andhra Pradesh was less.
KPTCL informed that it was due to non-transmission of the signal from Hoody and Somnahally due to pending works which were expected to be completed by February. APTRANSCO informed that due to the presence of alternate sources for some of the feeders identified for TK-1 SPS, desired load relief was not obtained. New feeders had been identified for providing desired load relief and the scheme was submitted to OCC for approval.
Remedial measures taken : PGCIL-SR2 informed the following RM: The failure of GR-MR changeover of Pole-1 was analyzed, and it was found that the sequence had failed due to a sequence issue command to 20B10-Q2 and the same was rectified. The automatic GR-MR changeover of Pole-2 was successfully executed at 22:10hrs. KPTCL informed the following RM: At Hoody end: The error in mapping of O/V function trip to Trip BO had been rectified and tested the O/V function on 16.01.2021. Now, the O/V trip initiats master trip relay 86A. Direct trip signal was not configured for DR trigger in Main-1 relay at Devanahally end. The same had been rectified on 16.01.2021.
***
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1.1 Single Line Diagram of 220 kV Sabarigiri GS of KSEBL Annexure-B
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1.4 Single Line Diagram of 220/110 kV Lower Jurala HEP of TSGENCO Annexure-B
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1.5 Single Line Diagram of 220 kV Narendra Substation of KPTCL Annexure-B
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1.6 Single Line Diagram of 220 kV VSS of APTRANSCO Annexure-B
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1.8 Single Line Diagram of 230 kV MAPS GS of NPCIL Annexure-B
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Annexure-B 1.9 Single Line Diagram of 230 kV Checknaurani SS of TANTRANSCO
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1.11 Single Line Diagram of 230 kV Bhavini Station Annexure-B
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Annexure-C Status of Pending Implementation of PCSC Recommendations as on 02.03.2021 (up to 94th Meeting)
Meeting Details of Event Date & Time Reason PCSC Recommendations Utility responsible for Implementation Status of Implementation of PCSC Recommendations Remarks Latest Status No / (To be filled up by the Constituent) Index
Multi-Utilities
34/I/6 400/220 kV ICT-1 & 2 at 16-07-2014 As reported directional over current relay of ICT’s 1. Bus bar protection shall be provided by asset owner ( i.e KPTCL). KPTCL/ KPTCL Mail dated 27-05-2015: Pending Munirabad operated due to snapping of line jumper in PGCIL (SR-I) 1. KPTCL has taken action to provide bus bar protection to 220kV buses. --- (with KPTCL) 220kV Lingapur line. 2. Settings for main distance protection & Overcurrent protection shall be Pending examined and reviewed. 2. Over current relay Settings of ICTs to be reviewed by PGCIL. --- Pending 3. Time synchronization of the Substation shall be ensured. 3. --- Pending KPTCL Mail dated 29-07-2015: 1. Initial Tendering stage. --- Pending 2. --- Pending 3. --- Pending
KPTCL Mail dated on 23-01-2016: 1. Detailed estimate prepared for taking up the work. CEE, Transmission Zone, Gulbarga will take up necessary procurement and further execution. --- Pending 2. --- Pending with PGCIL (SR-I). 3. --- Pending
PGCIL (SR-I) Mail dated 14.07.2016: 2. Relay settings of all the stations in SRTS-1 were derived as per Ramakrishna Commettee recomendations and implemented" --- Completed.
KPTCL Mail dated 16.12.2017: 1) & 3). DPR is approved. Tender is to be called by CEE,TZ Kalaburgi --- Pending
Review Meeting dated 19.12.2017: 1. KPTCL informed that Tenders for providing BBP would be called in Jan-Feb, 2018; Supply of the same is targeted by September, 2018; Erection & Commissioning is targeted by January, 2019 --- Pending
3. PGCIL (SR-I) informed that time-synchronization of 220 kV side is in place. --- Completed.
KPTCL mail dated 19.12.2018: 1. DPR preapared for the work of providing Bus Bar Protection to 220kV buses at Guddadahally is approved. Tender is to be invited by CEE,TZ .
Review Meeting dated 20.12.2018: 1. Tender would be floated in January 2019. Works would be completed in 6 months after awarding PO.
Review Meeting dated 27.06.2019: 1. KPTCL informed that the work is expected to be completed by December 2019.
Page 1 of 52 Annexure-C 66/ II/ Tripping of 400/ 220 kV 11-06-2017 Triggering incident was failure of 220 kV 1. NTPC to disable high-set of DEFR on the 220 kV lines emanating from their NTPC-Ramagundam/ TSTRANSCO NTPC mail dated 07.12.2017: Pending 10 ICT’s – 3 & 4 at at 19:46hrs B-phase LA in ICT-3 LV extension feeder (220KV Ramagundam STPS. 1. High set DEFR on 220 KV lines is disabled ----Completed Ramagundam STPS line-2) at Malayalapalli substation 2. ---- Pending 2. NTPC/ TSTRANSCO to provide Line Differential Protection (with or without pilot) on 220 kV Ramagundam – Malayalapalli lines – 1 & 2 & 3. Review Meeting dated 19.12.2017: TSTRANSCO informed that the works are under progress, and are targeted to be completed in 3 months time.
TSTRANSCO MAIL DATED 20.01.2018: Line Differential Protection will be provided within 3 months i.e., by end of March, 2018.
TSTRANSCO MAIL DATED 20.04.2018: Line Differential Protection relays are under procurement and will be provided by end of May, 2018.
TSTRANSCO MAIL DATED 17.05.2018: Line Differential relays will be supplied to site by manufacturer by end of May, 2018 and erection will be completed by end of June, 2018.
TSTRANSCO MAIL DATED 12.10.2018: Inspection of the relays is completed and the relays are received at stores. Relays TSTRANSCO MAIL DATED 22.01.2019: Relays will be commissioned by end of February, 2019.
TSTRANSCO mail dated 22.06.2019: 2. Relay erection work is under progress and will be completed by end of July, 2019. TSTRANSCO mail dated 30.10.2019: LDP relays are available but commissioned was not done bue to non availability of carrier communication cable and will be done in 2 months i.e., by December, 2019.
TSTRANSCO mail dated 18.01.2020: LDP relays are available at site. carrier communication cable laying between the LDPs is procured and laying work is under progress and will be completed by end of January,2020. Commissioning of LDPs will be done by 2nd week of February, 2020.
TSTRANSCO mail dated 28.11.2020: 2. Still the telecom communication cable laying is under progress and will be completed by December 2020. After completion of cable laying, commissioning of LDPs will be done. --- Pending
Page 2 of 52 Annexure-C 69/I/2 Complete outage of 400kV 30-10-2017 at 400kV TPCIL - Nellore line-1 got tripped at TPCIL 1. TPCIL to configure DEF protection such that it remains in blocked condition TPCIL/ Review Meeting dated 19.12.2017: Pending [With TPCIL station 21:37 hrs end during failure of LA of Station Transformer-2 at as long as Distance Protection is active, and becomes active only when distance PGCIL (SR-I) PGCIL (SR-I) informed that they are waiting for written confirmation from TPCIL TPCIL] TPCIL. Running Units at TPCIL got tripped due to protection does not pickup. to complete procurement of LDP relays. To this, PCSC forum asked TPCIL to loss of evacuating line. 400kV TPCIL - Nellore PS submit written confirmation to PGCIL (SR-I) by 29.12.2017. PGCIL (SR-I) line-2 was under emergency shutdown 2.PGCIL (SR-I) to ensure healthiness of Carrier communication, and the set PUP assured that with receipt of above confirmation from TPCIL by Dec, 2017, they mode of carrier aided scheme operates reliably on TPCIL lines 1 & 2. would be able to complete the work by February, 2018.
APTRANSCO informed that they would be able to implement LDP from their & APGENCO side by April, 2018. In this regard, PCSC forum made it clear that the recommendation is about providing LDP as both Main-I & Main-II relays on all stated lines in Nellore Complex, ans asked all stakeholders to ensure & comply with the same.
PGCIL (SR-I) mail dated 20.06.2018: 2. PGCI(SR1) procuring LDP relays for retrofitting of Main-1&2 distance relays. Tenders are invited from bidders & tender floated. Technical bid opening in this week.
PGCIL (SR-I) mail dated 10.12.2018: 2. PO placed on M/s GE & TD India Ltd on 24.09.2018. Supply of relays will be completed by Jan'2019 and commissioning by Mar'19.
Review Meeting on 20.12.2018 & 27.06.2019: PGCIL (Sr-1) mail dated 31.10.2019: Retrofitting works completed in NPS-NCC-1&2, NPS-Nellore-1&2 Main-1 relay, NPS-TPCIL-1&2 lines completed. Confirmation for retrofitting of Main-2 relay in NPS-Nellore-1&2 lines to be received from SRPC. Presently both lines are bypassed at Nellore Bus-1&2 and connected to Tiruvalam SS by closing Tie CBs at Nellore end. Now lines are long lines as 400kV NPS-Tiruvalam-1&2. The same was discussed in 84th PCSC meeting. SRPC has to give concurrence.
PGCIL -SR-1 maild ated 17.12.2019: Retrofitting works completed in NPS-NCC-1&2, NPS-TPCIL-1&2 lines for both Main-1&2 relays. Issue to be closed
69/III/3 Tripping of 400 kV 02-10-2017 at Line tripped on B-ph to ground fault. A/R was 1) PGCIL (SR-I) and APTRANSCO to provide for Line Differential Protection APTRANSCO/ APTRANSCO maild ated 30.01.2018: Pending [with Kurnool(PG) – 02:03 hrs unsuccessful at both Kurnool (AP) and Kurnool as both the Main protections on 400 kV Kurnool (AP) – Kurnool (PG) lines 1 & PGCIL (SR-I) 1. Pending... PGCIL (SR-I)] Kurnool(AP) line-2 (PG) ends. 2 lines. 2.A/R scheme on 400kV Kurnool (PGCIL) feeder-2 will be checked after getting 2) APTRANSCO to furnish an action taken report w.r.t. resolving A/R non- LC. operation at Kurnool-AP end for the subject trippings and configure EL for capturing PDR operation at their 400 kV Kurnool-AP SS. APTRANSCO maild ated 24.04.2018 & 24.05.2018 & 26.06.2018: 1. Pending... APTRANSCO Mail Dated 18.12.2018: 1) Bays and lines pertains to PGCIL . 2) ---Completed. PGCIL (SR-I) mail dated 20.12.2018: 1) PO placed on M/s GE & TD India Ltd on 24.09.2018. Supply of relays will be completed by Jan'2019. APTRANSCO MAIL DATED 22.01.2019: Pending [with PGCIL (SR-I)]
PGCIL (SR-I) mail dated 07.06.2019: PGCIL(SR-1): This issue of retrofitiing of distance relays with LDP relays in Kurnool(PG) – Kurnool(AP) D/C lines has been discussed with our management. Our management is seeking approval for the same. You are requested to takeup this LDP issue in next TCC meeting.
PGCIL (SR-I) mail dated 30.10.2019: This issue of retrofitiing of distance relays with LDP relays in Kurnool(PG) – Kurnool(AP) D/C lines has been discussed with our management. Our management is seeking approval for the same. You are requested to takeup this LDP issue in next TCC meeting.
PGCIL -Sr-1 mail dated 17.12.2019: This issue of retrofitiing of distance relays with LDP relays in Kurnool(PG) – Kurnool(AP) D/C lines has been discussed with our management. Our management is seeking approval for the same. SRPC/PCSC may please allow the POWERGRID to book the expenditure in any ongoing/upcoming projects.
PCSC on 18.12.2019: PCSC forum decided to forward the issue to SRPC TCC meeting
PGCIL-SR-1 mail dated 21.01.2021: This issue of retrofitiing of distance relays with LDP relays in Kurnool(PG) – Kurnool(AP) D/C lines has been discussed in TCC meeting. Accordingly order placed on M/s GE for supply and commissioning of relays. Target date: 30.04.2021.
Page 3 of 52 Annexure-C 69/III/7 Tripping of 220 kV 12-10-2017 at Line tripped on B-Ph to earth fault. A/R was KPTCL and APTRANSCO to sort out issues relating to incongruence in APTRANSCO/ KPTCL APTRANSCO maild ated 15.12.2017: Pending Ragulapadu – Alipura line 01:30 hrs successful at Regulapadu and breakers at Alipura denoting R, Y, B phases of the electric supply on their respective sides. APTRANSCO would extend support and requirements if any ,for the [with KPTCL ] end got tripped. rectification proposed by KPTCL. Review Meeting dated 19.12.2017: It was noted that the original Gooty - Lingapur line got LILOed at BTPS, Alipura, and Ragulapadu. It was also noted that Phase Discrepancy is being observed in Ragulapadu - Alipira section only. When enquired about the same, KPTCL informed that they would examine the issue in detail, and would inform the action lan proposed by next PCSC-71 meeting. On this, APTRANSCO was also asked to render all help required from their side to KPTCL.
APTRANSCO maild dated 30.01.2018: APTransco world extend required support . APTRANSCO maild dated 24.04.2018 & 24.05.2018 & 26.06.2018: AP Transco would extend required support for attending, phase discrepancy issue in ragulapadu-Alipura line by KPTCL. APTRANSCO Mail Dated 25.07.2018: To be attended by KPTCL as discussed in 75th PCSC meeting. KPTCL mail dated 19.12.2018: Phase mis match issue is to be sorted out jointly by KPTCL/ APTRANSCO/ KPCL.
Review Meeting on 20.12.2018: PCSC forum decided that concrete action in this respect to be initiated in 2 months by KPTCL alongwith APTRANSCO.
APTRANSCO MAIL DATED 22.01.2019: Pending [with KPTCL ]
Review Meeting on 27.06.2019: KPTCL informed that the work is expected to be completed by August 2019.
KPTCL mail dated 12.02.2020: Correction is to be incorporated in the primary side, procurement of required materials under progress.
76/II/9 Tripping of 230 kV 13-06-2018 at Y-phase to earth fault occurred in line. At 230 kV 1) TANTRANSCO to provide double-bus operation at their 230 kV Thiruvalam TANTRANSCO/ APTRANSCO 1) TANTRANSCO Mail dated 29.08.2018 & 11.09.2018: Pending [with Thiruvalam - Chittoor line 18:55hrs Tiruvalam end, breaker was under lockout leading SS. Material supplied and work to be taken up ---Pending TANTRANSCO] to operation of LBB protection. 2) APTRANSCO Mail dated 24.09.2018: 2) APTRANSCO to replace the existing static relays with suitable numerical The static relays were replaced with Numerical relay on all 220 kV feeders at 220 relays for various line protections at their 220 kV Chittoor SS. kV SS chittoor.---Completed
TANTRANSCO Mail dated 11.12.2018: Due to space constraint, the equipments could not be erected.
Review Meeting on 20.12.2018: In view of Tiruvalam being inter-state sustation, TANTRANSCO was asked to prvodie double-bus operation at their 230 kV Tiruvalam SS.
APTRANSCO MAIL DATED 22.01.2019: Pending [with TANTRANSCO]
TANTRANSCO MAIL DATED 23.01.2019 & 19.03.2019: Feasibility for providing hybrid breaker / shifting of bays will be studied & action will be taken. Time upto Sep 2019
TANTRANSCO MAIL DATED 13.06.2019: 1. Bus segregation will be ensured by providing bus coupler bay by extending the existing Bus.Time line 31.12.2019.
TANTRANSCO mail dated 18.07.2019 & 26.07.2019: 1. Bus segregation will be ensured by providing bus coupler bay by extending the existing Bus.Time line 31.12.2019.
TANTRANSCO mail dated 12.02.2020 & 20.05.2020 15.06.2020 & 07.07.2020 & 28.09.2020: 1. Bus segregation will be ensured by providing bus coupler bay by extending the existing Bus.Time line rquested upto 31.12.2020.
TANTRANSCO mail dated 11.11.2020 and 18.01.2021: Due to inadequate space,it is not fesible to provide hybrid BC breaker.
Page 4 of 52 Annexure-C 78/I/2 Complete outage of 220 kV 17-09-2018 at 220kV lines connected to Nagjheri PH got tripped 1. SLDC/KPTCL to be pro-active in issuing necessary directions that help in KPCL/ KPTCL KPTCL mail dated 19.12.2018: Pending Nagjheri PH and 220/110 14:37hrs due to successive transient faults. Running Units #3 expeditious restoration of the tripped lines based on the prevailing conditions 3). Nagzari-Bidnal PLCC link is healthy --- Completed. kV Ambewadi Substation. and #4 at Nagjheri got tripped on over frequency and grid security. 1.--- Pending protection operation due to loss of evacuating lines 2. --- Pending resulting in complete outage of 220 kV Nagjheri. 2.KPCL to implement A/R enabled on all 220 kV lines emanating from their 220 kV Nagjheri being the only source to 220kV 220 kV Nagjheri PH, with the help of KPTCL, by December, 2018. In the event Review Meeting on 20.12.2018: Ambewadi station, since 220kV Ambewadi of non-amenability of the existing PZ1000 relays in providing A/R feature, 1. & 3. Completed Narendra line 1&2 were under shutdown during KPCL shall take steps to retrofit them with suitable relays that support A/R. 2. Pending antecedent condition, tripping of Units at 220 kV Nagjheri resulted in the loss of supply to 220 kV 3. KPTCL to restore PLCC carrier communication on 220 kV Nagjheri – Bidnal KPCL mail dated 24-12-2018: Ambewadi SS. line at the earliest 1) --- Completed
2) Proposal will be taken up for replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 shortly, after availing necessary admnistrative approval...Pending
3) Completed
KPCL mail dated 23.01.2019: 1. Completed
2. Letter addressed to site to take up the proposal for replacement of PZ1000 line distance relays. KPCL mail dated 23.03.2019: 1). COMPLETED 2) Proposal will be taken up for replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850. Prepration of specification is under progress. 3) COMPLETED
KPCL mail dated 13.05.2019: 1) & 3) Completed 2) Budgetary offer obtained for replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850. Preparation of estimation and specification is under progress.
KPCL mail dated 25.06.2019: 1) & 3) Completed 2) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. Approval of NLDC for DPR is awaited. Further, availing administrative approval for issue of NIT for replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 and preparation of estimation and specification is under progress.
KPCLReview mail Meeting dated on 16.07.2019: 27.06.2019: 1) & 3) Completed 2) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. Approval of NLDC for DPR is awaited. However, administrative approval for issue of NIT for replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 obtained. Preparation of technical specification is under progress. KPCL mail dated 30.10.2019: 2)Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. Approval of NLDC for DPR is awaited. NIT issued through e-portal on 16.09.2019. Pre- bid meeting was held on 10.10.2019. Finalising of replies to pre-bid queries is in progress.
KPCL mail dated 17.12.2019: 2) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. Approval of NLDC for DPR is awaited. NIT issued through e-portal on 16.09.2019. Cover- 1 opened on 02.12.2019. Technical evaluation is in progress.
KPCL mail dated 11.02.2020: 2) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. Approval of NLDC for DPR is awaited. NIT issued through e-portal on 16.09.2019. Tender evaluation is in progress.
KPCL mail dated 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: 2) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. NIT issued through e-portal on 16.09.2019. Tender evaluation is completed. Approval of NLDC for DPR is awaited for placing PO on L1 agency.
Page 5 of 52 Annexure-C 78/II/16 Multiple trippings at 31-08-2018 Triggering incident was B-E fault in 220 kV 1)KPTCL to examine the reasons for tripping of more than one Unit (Units – 3 KPTCL/ KPCL Review Meeting on 20.12.2018: Pending 220kV Nagjheri PH at 11:49 hrs Nagjheri - Ambewadi line-1. As per the information & 6) on SPS operation at Nagjheri PH during subject trippings, and furnish a 1. KPTCL I formed that SPS scheme finalisation shall be completed in one month received, after tripping of 220 kV Naghjeri - report on the same along with remedial action taken to PCSC forum. time --- Pending Ambewadi line-1, 220 kV Naghjeri Ambewadi line#2 got overloaded. This resulted in the tripping 2)KPCL to employ a suitable time delay of 50 – 60 msec in operation of REF KPCL mail dated 24-12-2018: of Nagjheri Generating Units #3 and 6 on SPS protection for the GT of Unit-2 at their Nagjheri PH. 2) Time delay of operation is not changed. However, the external NCT is used for operation. At the same time, Unit #2 got tripped on REF protection against earlier internal NCT for REF, to avoid tripping due to REF operation. malopration --- Completed.
KPCL mail dated 23.01.2019: 1) It shall be reviewd and Implemented by KPCL in coordination with KPTCL. 2)....Completed.
KPCL mail dated 23.01.2019: 1) It shall be reviewd and Implemented by KPTCL in coordination with KPCL.
KPCL mail dated 10.05.2019 & 25.06.2019 & 30.10.2019: 1) Letter addressed to KPTCL RT dated: 25.03.2019 for review and implementation of SPS at NPH. Reply is awaited.
Review Meeting on 27.06.2019: 1. KPTCL informed that Nagjheri SPS has to be studied in the event of configuration changes and outcome of the same will be intimated soon . KPCL mail dated 16.07.2019 and 17.12.2019 and 11.02.2020: 1) Letter addressed to KPTCL RT dated: 25.03.2019 for review and implementation of SPS at NPH. Reply from KPTCL is awaited. 2)Completed.
KPTCL mail dated 12.02.2020: The logic is being reviewed by SRLDC by conducting system studies for the changed network configuration.
KPTCL mail dated 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: 1) Letter addressed to KPTCL RT dated: 25.03.2019 for review and implementation of SPS at NPH. Reply from KPTCL is awaited. 2)Completed.
79/I/2 Complete outage of 230/ 05-10-2018 at Triggering incident was B-phase fault at 230kV 1) TANTRANSCO to take steps to implement multi-bus, multi-zone operation TANTRANSCO/ APTRANSCO TANTRANSCO Mail dated 11.12.2018: Pending [with 110 kV Gummidipoondi 00:42 hrs Gummidipoondi Substation due to which 230kV (Double-bus operation) at their 230 kV Gummidipooindi SS by December, 1. TANTRANSCO: Estimate sanctioned for replacement of defective isolator TANTRANSCO] Substation Bus-1 Bus-bar protection operated. 230kV 22018. status feedback. Work under progress...... Pending Gummidipoondi Station was under single bus 2.Earth value of 110kV earthmat has been improved & 230kV side earthmat operation, hence operation of Bus-bar protection 2) TANTRANSCO to check if the Gummidipoondi substation is adequately work under progress. Lightning mask earthing renovation under resulted in tripping of all connected elements. protected from lightning-strokes by providing requisite no. of lightning masts execution...... Pending and/ or earth-wire caging. 3...... Pending
3) APTRANSCO was asked to verify & correct the settings employed for APTRANSCO Mail Dated 18.12.2018: distance protection at Sullurpeta and configure DR’s & EL’s of all Protection Relays settings reviewed and need to be revised due to change of line length DR Relays at their Supllurpet SS properly for recording only the mandated & EL's of Main-1 (P444) relay configured properly. Main-2 (D60) relay to be protections & digital signals. configured.
Review Meeting on 20.12.2018: 1 & 2). TANTRANSCO informed that Work will be completed by March 2019.
3. APTRANSCO informed that work will be completed by February 2019.
APTRANSCO MAIL DATED 22.01.2019: Collecting the details of adjacent feeders connected to Gummadipudi for computing revised relay settings.
TANTRANSCO MAIL DATED 23.01.2019: APTRANSCO mail dated 15.03.2019: 3. Revised relay settings were implemented on 16/02/2019 ---Completed
TANTRANSCO MAIL DATED 19.03.2019: New 230kV isolators have been allotted for replacement of defective isolators. Hence time line requested upto June.2019.
TANTRANSCO MAIL DATED 13.06.2019: 1. New 230kV isolators have been allotted for replacement of defective isolators. Hence time line requested upto Sep.2019.
Review Meeting on 27.06.2019: 1. New 230kV isolators have been allotted for replacement of defective isolators. Hence time line requested upto Sep.2019. 2. & 3. Completed
TANTRANSCO mail dated 18.07.2019 & 26.07.2019: 1. 1New 230kV isolators have been allotted for replacement of defective isolators. Hence time line requested upto Sep.2019
Page 6 of 52 79/I/2 Complete outage of 230/ 05-10-2018 at Triggering incident was B-phase fault at 230kV 1) TANTRANSCO to take steps to implement multi-bus, multi-zone operation TANTRANSCO/ APTRANSCO Pending [with 110 kV Gummidipoondi 00:42 hrs Gummidipoondi Substation due to which 230kV (Double-bus operation) at their 230 kV Gummidipooindi SS by December, TANTRANSCO] Substation Bus-1 Bus-bar protection operated. 230kV 22018. Gummidipoondi Station was under single bus operation, hence operation of Bus-bar protection 2) TANTRANSCO to check if the Gummidipoondi substation is adequately resulted in tripping of all connected elements. protected from lightning-strokes by providing requisite no. of lightning masts and/ or earth-wire caging.
3) APTRANSCO was asked to verify & correct the settings employed for distance protection at Sullurpeta and configure DR’s & EL’s of all Protection Relays at their Supllurpet SS properly for recording only the mandated protections & digital signals.
Annexure-C TANTRANSCO mail dated 12.02.2020: New 230kV isolators have been allotted for replacement of defective isolators. Hence time line requested upto March 2020.
TANTRANSCO mail dated 20.05.2020 & 07.07.2020: New 230kV isolators have been allotted for replacement of defective isolators. Hence time line requested upto 31.12 2020.
TANTRANSCO mail dated 28.09.2020 & 11.11.2020: Programmed to rectify / replace the sluggish 230kV Isolators in the bus coupler breaker and double bus operation will be bring into service before 31.12.2020.
TANTRANSCO mail dated 18.01.2021: It is programmed to avail LC in Gummidipoondi bus on 26.01.2021 to Check the alignment of bus selection isolators. Further action is being taken to rectify / replace the sluggish 230kV Isolators in the bus coupler breaker and double bus operation will be bring into service before 31.03.2021.
83/I/1 Complete outage of 230kV 11-03-2019 Triggering incident was Y-phase CT blast in 230kV 1. TANTRANSCO is recommended to submit action plan to provide Multi-Bus TANTRANSCO/ PGCIL (Sr-2) TANTRANSCO MAIL DATED 13.06.2019: Pending[PGCIL- Veeranam substation of at 00:55Hrs Tirunelvelli (Abhishekpatty) – Veeranam Ckt-1. operation/ Hybrid breakers at 230kV Veeranam SS with clear timelines. 1.Provision of bus coupler breaker is not feasible due to space constaint. SR-II] TANTRANSCO 230kV Trirunelvelli – Veeranam Ckt-1 and 2 2. TANTRANSCO to revise the distance zone settings at Tiruneveli SS for 2&3. Tirunelveli end maintained by PGCIL. tripped. Two faults were observed from the PMU 230kV Veeranam – Tirunelveli line to overcome the problem of relay overreach 4. Report will be sent. plot. During the second fault, delayed fault and share the same with SRPC. clearance of 400ms was observed. As reported, other 3. TANTRANSCO to take definite measures ensure the time synchronization of Review meeting on 27.06.2019: connected feeders 230kV Veeranam – Kodikur ckt- relays at Tirunelveli end. 1.Provision of bus coupler breaker is not feasible due to space constaint. 1&2 and 230kV Veeranam – Kayathar tripped on 4. TANTRANSCO to submit equipment failure report of the failed CT to CEA. 2. Will be informed Zone -2 protection. 3. Time synchronisation will be ensured. 4. Report will be sent.
TANTRANSCO mail dated 19.07.2019, 12.02.2020 & 20.05.2020 & 15.06.2020: 1.Provision of bus coupler breaker is not feasible due to space constaint. 2&3. Tirunelveli end maintained by PGCIL. 4. Report sent to CEA. -- Completed
TANTRANSCO mail dated 28.09.2020: 1.Provision of bus coupler breaker is not feasible due to space constaint. - Dropped 2. & 3. PGCIL (Sr-2) to update 4. Completed
TANTRANSCO mail dated 11.11.2020 and 18.01.2021: 1. 1.Provision of bus coupler breaker is not feasible due to space constaint. 2&3. Tirunelveli end maintained by PGCIL. 4. Report sent to CEA. -- Completed
83/I/6 Complete outage of 220kV 10-04-2019 Y and B-phase earth isolator switch blades of 1. KPTCL is recommended to revise the SPS at Nagjheri, (to accommodate a KPTCL/ KPCL KPCL mail dated 25.06.2019: Pending Hubli substation of KPTCL at 18:09Hrs 220kV Hubli-Bidnal ckt-1, got closed due to failure new condition with high flow and low time delay) in consultation with SRPC 2) Carrier aided protection is enabled on all 220kV lines emanating from NPH and 220kV of locking mechanism during heavy wind and rain and SRLDC. ___Completed Nagjheri Power station of conditionsresulting in bus fault. Bus bar protection 2. KPCL in coordination with KPTCL is recommended to provide at least one KPCL operated and all connected elements tripped. There main protection as carrier aided three zone distance protection on the 220kV Review Meeting on 27.06.2019: was lines emanating from Nagjheri GS. 1. KPTCL informed that Nagjheri SPS has to be studied in the event of complete loss of supply at 220kV Hubli station since configuration changes and outcome of the same will be intimated soon the station was on single bus operation. At thesame time, 220kV Nagjheri-Ambewadi ckt-1 and 220kV KPCL mail dated 16.07.2019 & 30.10.2019: Nagjheri – Bidnal tripped on overcurrent 1. under progress protection. Since 220kV Nagjheri – Ambewadi ckt-2 2. Completed and 220kV Nagjheri-Kodasalli ckt-1 &2 wereunder shutdown in the antecedent due to maintenance, KPCL mail dated 17.12.2019 and 11.02.2020 & 21.05.2020 & 27.07.2020 & running units #1,4,5 and 6 tripped due to 28.09.2020 & 26.11.2020 & 22.01.2021: loss of evacuating lines. This resulted in complete 1) To be furnished by KPTCL loss of supply at 220kv Nagjheri station. 2)Completed.
KPTCL mail dated 12.02.2020: The logic is being reviewed by SRLDC by conducting system studies for the changed network configuration
83/II/9 Tripping of 400 kV 10-03-2019 at Line tripped on operation of overvoltage stage-1 PGCIL (SR-II) to submit action plan regarding replacement of CT’s for 400Kv PGCIL (SR-II)/ KPTCL PGCIL (SR-I) mail dated 07.06.2019: Pending GUTTUR - NARENDRA - 18:03hrs protection at Guttur end and DT received at Guttur Narendra line -1 at Guttur end. PGCIL (SR-II) to sort out the time sync Line belongs to PGCIL(SR-2) 1 Narendra end. Voltages at Guttur end: Vr-254kV, issues in DR and EL at Narendra end. Vy-252kV, Vb-246kV. As per voltage grading, Review meeting on 27.06.2019: 400kV Guttur Narendra line-2 should trip first. PGCIL(SR-II) informed that R & Y ph CVT replaced on 25.05.2019. Time syncronisation has to be attended by KPTCL.
Page 7 of 52 Annexure-C 84/I/1 Complete outage of 230kV 18-05-2019 at Triggering incident was Y phase to Earth fault in 1.TANTRANSCO may take immediate measures to attend the problem in LBB TANGEDCO/ TANTRANSCO TANTRANSCO mail dated 26.07.2019: Pending NCTPS Generating Station 04:39 hr. 220 kV NCTPS Tondiarpet line-2. Due to mal- wiring that is extending trip during A/R within one month. 1 & 2.Inbuilt LBB function will be enabled in the new distance relays. of TANGEDCO operation of LBB protection (of Tondiarpet line-2) 2. TANTRANSCO is recommended to send a detailed report regarding the A/R 3. will be ensured. at NCTPS end, all the connected elements of bus status (availability /enabling)on all lines emanating from 230kV NCTPS GS and 4.230kV Kilpauk was operated radially for avoid overloading in the adjacent zone-3 got tripped. Due to loss of evacuating lines, enable A/R in all lines emanating from 230kV NCTPS GS. feeders due to cable fault in the area.Normally all feeders are operated as grid running units at NCTPS unit#1 and 2 got tripped. 3.TANGEDCO in coordination with TANTRANSCO may take definite feeders. measures to ensure time synchronization of all relays with GPS signal at NCTPS end and remote ends at the earliest. TANTRANSCO mail dated 12.02.2020: 4. It was also suggested that possibility of backing down of generation, in the 1. LBB wiring set right and operation of the same has been verified for its event of unavailability of many feeders, in particular when radial feeders only healthiness. -- Completed are in service, may be looked at. 2. Since the CBs and the Control & Relay Panels (CRP) are very old and commissioned during 1993. The Distance relays even though are numerical due to ageing its display and resetting keys are faulty. Hence it is proposed to replace the CBs & CRPs with new CBs and Protection relay panel with SAS. A.R will be put into service after replacing the CB & CRP. 3. Time synchronisation of Protection relays is being carried out . The work is under progress.
TANTRANSCO mail dated 20.05.2020 & 15.06.2020 1. complied . 2. Since the CBs and the Control & Relay Panels (CRP) are very old and commissioned during 1993. The Distance relays even though are numerical due to ageing its display and resetting keys are faulty. Hence it is proposed to replace the CBs & CRPs with new CBs and Protection relay panel with SAS. A.R will be put into service after replacing the CB & CRP. 3. GPS commissioned
TANTRANSCO mail dated 28.09.2020: 1. complied . 2. Since the CBs and the Control & Relay Panels (CRP) are very old and commissioned during 1993. The Distance relays even though are numerical due to ageing its display and resetting keys are faulty. Hence it is proposed to replace the CBs & CRPs with new CBs and Protection relay panel with SAS. A.R will be put into service after replacing the CB & CRP. 3. GPS commissioned 4. TANGEDCO to reply - Pending
TANGEDCO mail dated 11.11.2020: 4. House Load operations are available in all the 3 units of NCTPS - 1 . Generators can able to supply their own auxiliary load alone during this period and they can be synchronised to the grid when the situation is stable. But due to sudden change in turbine and boiler parameters house load operation could not be possible at all times (Old Turbine and Boiler control logic). (Feeders in Bus-Section I & II are already in tripped condition and the whole generation is fed through Bus-Section - III , due to the tripping of this, load evacuation problem got arise and consequent Unit tripping are happened) - Complied Note: 1) On that day Unit - II is in house load for 7 Mins, Unit - I is in house load for 1 Min and then both the units are hand tripped due to un controlled turbine and boiler parameters. 2) Unit-III turbine got tripped due to overspeed.
TANTRANSCO mail dated 11.11.2020: 2. Since the CBs and the Control & Relay Panels (CRP) are very old and commissioned during 1993. The Distance relays even though are numerical due to ageing its display and resetting keys are faulty. Hence it is proposed to replace the CBs & CRPs with new CBs and Protection relay panel with SAS. A.R will be TANTRANSCO mail dated 18.01.2021: 1, 3, 4. Complied 2. . Since the CBs and the Control & Relay Panels (CRP) are very old and commissioned during 1993. The Distance relays even though are numerical due to ageing its display and resetting keys are faulty. Hence it is proposed to replace the CBs & CRPs with new CBs and Protection relay panel with SAS. A.R will be put into service after replacing the CB & CRP.
84/II/29 Frequent tripping of 220 01-05-2019 at B-N FAULT It was noted that no representative of APGENCO attended the meeting. APGENCO/ TSGENCO/ TSTRANSCO/ APTRANSCO APGENCO informed vide mail dated 26.05.2020 that The tine maintenance is Pending kV KTPS –Lower Sileru 16:04 hr. B-N FAULT For the subject line, the following shall be carried out by TSGENCO in co- under the purviewof AP TRANSCO & TS TRANSCO . Most of the tripping fault line 04-05-2019 at B-N FAULT ordination with APGENCO: dista nce are under the coverage of TS TRANSCO • 14:48 hr. B-N FAULT (i) End-to-end communication for DT/ permissive & other signals may be 05-05-2019 at R-N FAULT ensured by testing at boththe ends. TSTRANSCO mail dated 28.11.2020: 11:29 hr. R-B FAULT (ii) Healthiness of PLCC system components (hardware and software) at both Recently the line is made LILO at 400/220kV Asupaka susbstation. The tripping 06-05-2019 at R-B FAULT ends shall be checked and faulty components shall be repaired/ replaced. details are already being submitted and only few trippings are under 13:14 hr. B-N FAULT APTRANSCO in coordination with TSTRANSCO to ensure frequent patrolling TSTRANSCO jurisdiction. Frequent patrolling is being carried out at 09-05-2019 R-B FAULT and proper maintenance of ROW by attending all tree clearance issues. TSTRANSCO end. at13:58 hr. 12-05-2019 at11:10 hr. 15-05-2019
Page 8 of 52 Annexure-C 85/II/14 Tripping of 230kV Theni- 29-05-2019 at 3 phase to earth fault occurred in line. Tripped on For the subject line, the following shall be carried out by TANTRANSCO in TANTRANSCO/ KSEBL TANTRANSCO mail dated 12.02.2020: Complied Sabarigiri line 18:39 hrs ground over current protection 67N at Sabarigiri and coordination with KSEBL: The PLCC link between 230KV Theni – Moozhiyar feeder is healthy condition Zone-2 at Theni end. (i) End-to-end testing for DT/ permissive & other signals may be ensured by and non-actuation of Carrier Protection during the fault on 29-05-2019 at 18:39 testing at both the ends. Hrs was due to the fault sensed in Zone-2 reach at Theni SS and Earth fault at (ii) Healthiness of PLCC system components ( hardware and software) at both Moozhiyar SS. the ends shall be checked and faulty components shall be repaired/ replaced . KSEBL mail dated 11.02.2020: PLCC system in SBTN feeder at Sabarigiri is not working well. Purchase process for the new panel is under progress.It will be commissioned by April 2020.
TANTRANSCO vide mail dated 20.05.2020 informed that: ZIV make new carrier set is erected and ready for commissioning . KSEB may procure the same make ( ZIV) the link will be commissioned.
TANTRANSCO mail dated 18.02.2021: new carrier set was commissioned
85/II/26 Tripping of 400kV 14-06-2019 at Line-1 tripped on Y-Phase to earth fault due to Y- 1. APTRANSCO is recommended to submit Equipment failure report (LA APTRANSCO/ GMR APTRANSCO maild ated 03.10.2019: Pending Vemagiri-GMR line-1&2 09:33 hrs Phase LA failure at Vemagiri end. Line-2 tripped at failure) to CEA. 1. Equipment (LA failure) Failure report submitted to CEA on 12.07.19. GMR end only 2.GMR is recommended to submit a report regarding tripping of 400kV ---Completed Vemagiri-GMR line-2 at GMR end along-with the related tripping files. 2. Pending
86/II/7 Tripping of 220 kV KTPS - 8-7-2019 at Line tripped on B-phase to earth fault. As per FIR, For the subject line, the following shall be carried out by APGENCO in APTRANSCO APGENCO mail dated 26.05.2020: Pending (with APTRANSCO) Lower Sileru-1 10:45 hrs there was zone-2 operation at KTPS coordination with TSGENCO: Aulo Re closure is disabled due to generating station . Carried aided protection i. End-to-end testing for DT/ permissive& other signals may be ensured by extended from relay to PLCC panel is checked and found ok. The PLCC testing at both the ends. equipment is under the purview of APTRANSCO, tit is kept in OFF condition at ii. Healthiness of PLCC system components (hardware and software) at both the both ends. It was mentioned that the same will be kept in service in short time as ends shall be checked and faulty components shall be repaired/ replaced . the 220kV Lower Sileru KTPS feeder becoming LILO at 400 KV Asupaka sub- Station.
88/IV/4 Tripping of 220kV Chillakallu 17-10-2019 at 13:30 Triggering incident was Y phase to B phase fault in the line. At The following shall be carried out by TSTRANSCO in coordination with APTRANSCO: TSTRANSCO,/ APTRANSCO TSTRANSCO mail dated 11.02..2020: Pending Time sync?? Suryapet line-1 Hr. Chillakallu end, as per the report submitted it is mentioned that a) End-to-end testing for DT/ permissive & other signals may be ensured by testing at both the At our end MRT & Telecom wing are ready to carry out end to end testing. Zone-1 distance protection operated. However, DR is not ends. Waiting for confirmation from APTRANSCO end to carry out testing. available to verify the same. At Suryapet end, Zone-2 distance b) Healthiness of PLCC system components (hardware and software) at both the ends to be protection operated and carrier was not received. Failure of checked and faulty components to be repaired/ replaced. TSTRANSCO mail dated 28.11.2020: carrier aided protection at Suryapet end needs review. c) Time synchronization of relays at both ends. a) & b) End to end testing is carried out and A/R function is kept into service.
89/I/6 Complete loss of supply at 220 16-01-2020 at • Triggering incident was Y-phase jumper cut in 220 i. PGCIL (SR-2) to disable Broken conductor trip and enable Broken conductor alarm. PGCIL (Sr-2)/ KPTCL KPTCL mail dated 22.05.2020: Pending DR configuration and broken kV Kolar, 220 kVMalur and 220 09:58 Hr. kV Kolar (KAR) – Kolar (PG) line-1. ii. KPTCL to configure all DR digital channels in relay DR and submit the SPS scheme 2. Logic implemented for SPS provided at 220kV Kolar Sub station is already conductor trip? kV Sarjapur stations. • 220 kV Kolar (KAR) – Kolar (PG) Line-2 tripped implemented at 220 kV Kolar (KAR) SS. mailed to SRPC/SRLDC at Kolar (KAR) end only. • There was complete loss of supply at 220 kV Kolar, Malur and Sarjapur stations.
90/II/17 Tripping of 400kV Guttur 15-03-2020 at Line tripped on operation of OV St-1 protection PGCIL-SR-2 to configure DR and EL at Hiriyur end for the subject line for DT send and DT PGCIL (SR-2)/ KPTCL KPTCL mail dated 04.08.2020: Pending –Hiriyur Line-2 18:03Hr. operation at Hiriyur end and was holding at Guttur receive signal. End to end testing is yet to be carried out. end. From DR of Hiriyur end, voltages observed are: For the subject line, the following shall be carried out by PGCIL-SR-2 in coordination with KPTCL and revert back to the forum: Vr-251kV, Vy-248kV and Vb-248kV. Non tripping i. End-to-end testing for DT/ permissive& other signals to be ensured by testing at both the ends. of line at Guttur end needs review. ii. Healthiness of PLCC system components (hardware and software) at both the ends shall be checked and faulty components shall be repaired/ replaced.
90/V/1 220kV KTPS-Lower Sileru line-1 10 -02-2020 at V. Frequent tripping of 220kV KTPS-Lower Sileru ATRANSCO in coordination with TSTRANSCO to ensure frequent patrolling and proper APTRANSCO/ TSTRANSCO TSTRANSCO mail dated 28.11.2020: Pending and 220kV KTPS V- Lower 11:34 Hr. line-1 and 220kV KTPS V- Lower Sileru line-2 maintenance of ROW by attending all tree clearance issues. KTS-LSL is made LILO at Asupaka SS. Sileru line-2 05-03-2020 at during February 2020 to April 2020. Frequent patrolling is being carried out from TSTRANSCO end. 12:00 Hr. 07-03-2020 at 13:25 Hr. 11-03-2020 at 15:01 Hr. 15-03-2020 at 12:04 Hr. 18-03-2020 at 12:25 Hr. 22-03-2020 at 10:50 Hr. 08-02-2020 at 12:35 Hr. 15 -02-2020 at 13:29 Hr. 16-02-2020 at 11:54 Hr. 22-03-2020 at 11:16 Hr. 27-03-2020 at
Page 9 of 52 Annexure-C 90/VI/1 Tripping of 220kV KTPS – 05-03-2020 at Frequent Tripping of 220kV KTPS – Nunna line ATRANSCO in coordination with TSTRANSCO to ensure frequent patrolling and proper APTRANSCO/ TSTRANSCO TSTRANSCO mail dated 28.11.2020: Pending Nunna line 13:44 Hr. during February 2020 to April 2020 maintenance of ROW by attending all tree clearance issues. Frequent patrolling is being carried out from TSTRANSCO end. 06-04-2020 at 13:39 Hr. 08-04-2020 at 16:53 Hr 10-04-2020 at 08:28 Hr 11-04-2020 at 15:03 Hr 18-04-2020 at 15:50 Hr
85/II/20 Tripping of 220kV Idukki- 05-06-2019 at Triggering incident was R-Y-Earth fault in the For the subject line, the following shall be carried out by TANTRANSCO in KSEBL/ TANTRANSCO TANTRANSCO mail dated 12.02.2020: Complied Udumalpet line 15:13 hrs line. Carrier aided protection not operated at coordination with KSEBL: Carrier set healthy at Udumelpet end. Healthiness of link will be checked after Udumalpet end. (iii) End-to-end testing for DT/ permissive & other signals may be ensured by getting confirmation from KSEB testing at both the ends. (iv) Healthiness of PLCC system components ( hardware and software) at both KSEBL mail dated 11.02.2020: the ends shall be checked and faulty components shall be repaired/ replaced . PLCC system in IDUD feeder at Idukki is not working well. Purchase process for the new panel is under progress.It will be commissioned by April 2020.
TANTRANSCO vide mail dated 20.05.2020 informed that: ZIV make new carrier set is erected and ready for commissioning . KSEB may procure the same make ( ZIV) the link will be commissioned.
TANTRANSCO mail dated 18.02.2021: new ZIV make Carrier set with Protection Coupler is erected, tested and commissioned on 19.08.2020 at 18.00 Hrs sucessfully both ends.
91/I/1 Complete outage of 220kV 04-04-2020 at • Triggering incident was R - Y fault in 220kV i. PGCIL(SR-2) to submit a report detailing reason for delayed pick up of fault at PGCIL(SR-2)/ KPTCL KPTCL mail dated 28.09.2020: Pending Gowribidanur SS and 14:15 Hrs Gowribidanur - KIADB line. Hiriyur end, non-picking of fault by Main-1 relay of Gauribidanur line-1, and to ii. 220kV Bus Bar Protection commissioned at Gowribidanur SS on 19.09.2020 220kV KIADB SS of • At 220kV Gowribidanur end, fault was sensed in configure zone pick up and trip in 220kV lines from 400/ 220kV Hiriyur SS. KPTCL Zone-2 and breaker didnot open because of ii. KPTCL to expedite commissioning of BBP at 220kV Gauribidanur SS and suspected breaker struck conditionand due to ensure time synchronization of relays at Madhugiri SS. absence of LBB/BBP protection at 220kV Gowribidanur end, fault was cleared by tripping of all the lines connected to 220kV Gowribidanur SS at remote ends on operation of Zone-3 distance protection. • This resulted in complete loss of supply at 220kV Gowribidanur SS. • Since 220kV KIABD SS was radially fed 220kV Gowribidanur SS, this further resulted in complete loss of supply at 220kV KIADB SS.
91/II/1 Tripping of 220kV- 04-04-2020 at • Triggering incident was Y N fault in 33kV cable i. PGCIL(SR-2) to intimate PCSC forum regarding OEM observations and RM PGCIL(Sr-2)/ KSPDCL Yet to be informed Pending PAVAGADA-KSPDCL line-08:46Hrs no.3 of KSPDCL 220/33kV SS-4. suggested regarding DEF operation by Main-2 Siemens relay at Pavagada end. 4 • Cable got tripped on operation of Overcurrent ii. KSPDCL to check PLCC and investigate the reason for non-receipt of DT at protection. their end. Time synchronisation of relays with GPS clock at KSPDCL SS need to • At the same time, 220kV Pavagada KSPDCL line- be ensured. 4 got tripped only at Pavagada end on operation of DEF protection.
91/II/3 Multiple Tripping of 400kV 07-04-2020 at • Triggering incident was B phase LA failure at i. PGCIL(SR-1) to evaluate the transient performance of CVTs at Raichur PG. PGCIL(SR-1)/ KPCL KPCL mail dated 26.11.2020: Pending lines at Raichur(PG) SS 19:04 Hrs Raichur(PG) end of 400kV Gooty-Raichur(PG) line- Time sync of DR with GPS at 400kV RaichurPG end for 400kV i) Pending 1. 400kVRaichurTPS-Raichur(PG) line-1 shall be ensured. ii) Sufficient time delays for NPS protection is adopted based on OEM • 400kV Raichur TPS - Raichur(PG) line-1 &2 and ii. KPCL to look into tripping of their HT equipment on negative phase sequence recommendations for HT equipments. This point may be dropped -- Completed 400kV Gooty-Raichur (PG) line-2 got tripped on current protection and to enable the same with sufficient time delay. iii) It will be configured during next shut down of lines. -- Pending operation of Overvoltage ST-2 protection at iii. KPCL is also recommended to trigger DR at 400kV RTPS GS during DT Raichur(PG) end and DT was sent to remote end. receipt. PGCIL-Sr-1 mail dated 21.01.2021: • Running units#5 and 7 at 400kV RTPS got tripped i. Pending- Facility not available with POWERGRID to evaluate transient during this event. performance of CVTs at Raichur PG. iii.Wiring issue b/n GPS and relay rectified and at present DR/Relay is time synchronised with GPS. - Completed
91/II/5 Tripping of 220kV- 19-04-2020 at • Triggering incident was B N fault in 33kV cable of i. PGCIL(SR-2) to intimate PCSC forum regarding OEM observations and RM PGCIL(Sr-2)/ KSPDCL Yet to be informed Pending PAVAGADA-KSPDCL line-15:23Hrs KSPDCL 220/33kV SS-3. suggested regarding DEF operation by Main-2 Siemens relay at Pavagada end. 3 • Cable got tripped on operation of Overcurrent ii. KSPDCL to check PLCC and investigate the reason for non-receipt of DT at protection. their end. • At the same time, 220kV Pavagada KSPDCL line- iii. Time synchronisation of relays with GPS clock at KSPDCL SS need to be 3 got tripped only at Pavagada end on operation of ensured. DEF protection.
Page 10 of 52 Annexure-C 91/II/13 Multiple Tripping in 09-05-2020 at • Triggering incident was B ph Bus-2 PT failure at i. PGCIL(SR-2) to intimate the forum regarding OEM observations and RM PGCIL(Sr-2)/ KSPDCL KPCL mail dated 28.09.2020: Pending 220kV/33kV KSPDCL SS 19:08Hrs 220kV KSPDCL SS no.4. suggested in respect of DEF operation of Main-2 Siemens relay at Pavagada end. ii) Sufficient time delays for NPS protection is adopted based on OEM 4 • Bus-2 BBP operated resulting in the tripping of all ii. PGCIL(SR-2) to check the zone settings of Pavagada – KSPDCL line, since it recommendations for HT equipments. This point may be dropped. the elements connected to Bus-2 at 220kV KSPDCL tripped in Zone-1 for a fault in remote SS. SS no.4. iii. KSPDCL to check PLCC and investigate the reason for non-receipt of DT at iii) It will be configured during next shut down of lines. • At the same time, RYBG fault occurred at 33kV their end. cable feeder no.6 of KSPDCL 220/33kV SS-3. iv. Time synchronization of relays with GPS clock at KSPDCL SS need to be • Cable got tripped on operation of Overcurrent ensured. protection. • At the same time, 220kV Pavagada KSPDCL line- 3 got tripped only at Pavagada end on operation of DEF protection.
91/II/19 Tripping of 400kV 22-05-2020 at • Triggering incident was B N fault in the line. i. TSTRANSCO to check A/R scheme at Dichipalli end and sort out the issue TSTRANSCO/ NTPC (Rmgdm) TSTRANSCO mail dated 28.11.2020: Pending Time sync?? Ramagundam – Dichipalli 12:39Hrs • At Ramagundam end, fault was sensed in Zone-1. with unwarranted reclosing of Main CB. i. LC was availed on 19-08-2020 and A/R scheme is verified. Wiring for 3phase line • Initially B pole breaker got opened, subsequently ii. NTPC and TSTRANSCO to sort out time sync issue of relays at both ends of A/R is removed. R and Y poles also got opened due to occurrence of the line. fault in Y phase. • At Dichipalliend,fault was sensed in Zone-1, B pole got opened and when there was subsequent fault in Y phase, instead of 3 ph trip, there was A/r attempt
Page 11 of 52 Annexure-C 91/II/20 Tripping of Bus-2 at 220kV 23-05-2020 at • Triggering incident was failure of HV side CT i. TSGENCO to revise zone settings of 220kV KTPS-Nunna line, since it tripped APTRANSCO/ TSGENCO Yet to be informed Pending Nunna SS of APTRANSCO 09:45Hrs connected to 220/132kV ICT-1 at Nunna. in Zone-1 for a fault in remote SS. • Bus bar protection of Bus-2 operated and all Bus-2 ii. APTRANSCO and TSGENCO to ensure time synchronization of relays with connected elements tripped. GPS at KTPS and Nunna SS.
91/II/21 Tripping of 400Kv 26-05-2020 at • Triggering incident was R N fault in the line. i. For the subject line, APTRANSCO in coordination with TSGENCO to carry APTRANSCO/ TSGENCO Yet to be informed Pending NarnoorSrisailam Left 16:32Hrs • Line tripped only at Narnoor end on receipt of DT. out the following and revert back to the forum: Bank • From DR of Narnoor end, Zone-2 pickup was a. End-to-end testing for DT/ Permissive& other signals to be ensured by testing observed. atboth the ends. b. Healthiness of PLCC system components (hardware and software) at both theends to be checked and faulty components to be repaired/ replaced. 91/III/1 Tripping of 400kV 01-04-2020 • Triggering incident was Y phase to Earth fault in the line. i. NLCIL to sort out issues regarding A/R operation of 400kV NLC TS2 Exp- NLCIL/ PGCIL(SR-2) NLCIL mail dated 21.11.2020: Pending NLC TS2 Exp- at 13:41 Hrs • At Pugalur end, fault was sensed in Zone1, A/r operated Puglaur line in consultation with OEM. Budgetory offer obtained from Siemens for commissioning the Mian-II relay with Puglaur line successfully and the line was holding. ii. For the subject line, PGCIL(SR-2), in coordination with NLCIL to carry out Siemens make by replacing the Micom-P437 relay. Workorder to be Placed • At NLC 2 Exp end, fault was sensed in ZOne-1, initally there the following and revert back to the forum: was opening of Y pole but subsequently R and B poles also got withM/s siemens . opened and A/r not operated. a. End-to-end testing for DT/ Permissive& other signals to be ensured by testing at both the ends. b. Healthiness of PLCC system components (hardware and software) at both the ends to be checked and faulty components to be repaired/ replaced 91/III/7 Tripping of 220kV 12-04-2020 • Triggering incident was B -N fault in the line. i. APTRANSCO to submit complete DR clearly showing A/R operation at APTRANSCO/ KPTCL Yet to be informed Pending Regulapadu – at 07:07Hrs • At Alipur end, line tripped on operation of Z1 distance Regulapadu end. Alipur line protection and A/r not operated. ii. KPTCL to expedite resolving of phase mismatch issue at Alipur and • At Regulapadu end, it is mentioned that A/r operated. subsequently enable A/R in the line at Alipur end However, the same couldn't be verified since DR at Regulapadu end is not submitted.
91/III/14 Tripping of 220kV 01-05-2020 • Triggering incident was R phase to Earth fault in the line. i. APTRANSCO and TSGENCO to ensure proper line clearances on the subject APTRANSCO/ TSGENCO Yet to be informed Pending Chillakallu- at 02:30Hrs • Line tripped only at Pulichintala end on operation of Zone-1 line. Pulichintala distance protection. ii. TSGENCO to enable A/R for the subject line at Pulichinthala end at the 18-05-2020 • A/r not operated at Pulichintala end earliest and inform PCSC forum. at 16:27Hrs
91/III/16 Tripping of 220KV 05-05-2020 • Triggering incident was B N fault in the line. i. TSGENCO to submit report regarding failure of carrier aided protection at APTRANSCO/ TSGENCO Yet to be informed Pending KTPS- at 13:05Hrs • At KTPS end, A/r is not in service and line tripped on KTPS end and to make all efforts to put A/R in service. NUNNA line operation of Zone-2 distance protection. ii. APTRANSCO to submit report regarding A/R non-attempt at Nunna end for • At Nunna end, Zone-1 operated and A/r not operated the subject line.
92/I/2 Complete outage of 220/33kV 25-06-2020 at 02:43 • Triggering incident was tripping of 220kV Pavagada - i. KSPDCL to share the value of real and reactive power flow through Pavagada KSPDCL/ PGCIL (Sr-2) Yet to be informed Pending KSPDCL SS-3 Hr. KSDPCL3 line due to overvoltage at 220kV Pavagada end. KSPDCL lines during the incidence. • Asthe only connected feeder tripped, there was complete ii. PGCIL (SR-2) to arrange for testing to ensure healthiness of communication outage at 220/33kV KSDPCL SS-3. Solar generation was not channel. there, since the event happened during night hours.
92/II/1 Multiple Tripping in 220kV 03-06-2020 at 14:01 • Triggering incident was failure of B phase LA of 220kV i. APTRANSCO to submit the line DR at Gunadala end for the tripping of APTRANSCO/ PGCIL(Sr-1) PGCIL-SR-1 mail dated 21.01.2021: Pending [ with Nunna SS of APTRANSCO Hr. Nunna- Gunadala line-2 (connected to 220kV Bus-2) in 220kV 220kV Nunna – Gunadala line-2 and submit report regarding non-operation of iii.PGCIL(SR-1): DR naming corrected as per scheme and DR standardized for APTRANSCO] Nunna station. CAT Zone-2 at Gunadala end. ICT-3 DOC & EF relay at Vijayawada SS on 03.07.2020. - Completed • Due to breaker problem in 220kV Nunna- Gunadala line at ii. APTRANSCO to ensure time synchronization of relays at Nunna end. Nunna end, LBB of Bus-2 operated resulting in tripping of all elements connected to 220kV Nunna Bus-2. iii. PGCIL (SR-1) to ensure proper naming of digital signals in the DR of 400/ • 400/220kV ICT-3 got tripped on operation of backup OC 220kV ICT-3 at Vijayawada. protection.
92/III/4 , 92/III/6,Tripping of92/III/8 220kV Chillakallu - 17-06-2020 at 01:21 • Triggering incident was R phase to Earth fault in the line. Line i. TSGENCO to enable A/R at Pulichintthala SS at the earliest. TSGENCO/ TSTRANSCO/ APTRANSCO TSTRANSCO mail dated 28.11.2020: Pending Pulichintala line Hr. tripped on operation of Zone-1 distance protection at both the ii. APTRANSCO and TSTRANSCO to ensure proper ROW for the line. ii. Thorough patrolling is carried out by TSTRANSCO on this feeder. ends. • A/R not operated at both ends.
92/V/1 Frequent Tripping of 220kV Jul-20 220kV Asupaka – Lower Sileru line tripped 13 times during i. APGENCO and TSTRANSCO to enable A/R at their respective ends for the APGENCO/ TSTRANSCO/ APTRANSCO TSTRANSCO mail dated 28.11.2020: Pending ROW? Asupaka – Lower Sileru July 2020. It has been reported that Auto reclose function at line. i. A/R is put into service on 04-11-2020 by carrying out end to end testing. 220kV Lower Sileru is kept out of service and same needs to be ii. APTRANSCO and TSTRANSCO to clear the trees/greenery in the right of reviewed. Remedial measures taken to avoid frequent tripping way ( to avoid vegetation faults) through periodic line patrolling and proper of the line may be apprised. ROW maintenance methods.
93/I/5 Complete outage of 220 31-08-2020 at 17:12 In the antecedent condition 220 kVNarendra Bus-1 and Bus-2 i. KPTCL to take up with Karnataka SLDC to ensure that Grid Disturbances on KPCL/ KPTCL KPCL mail dated 22.01.2021: Pending kVNagjheri GS,220 Hr. were under planned shutdown for maintenance works. account of operational issues do not occur in Kali (Nagjheri) complex, and be iii) Will be taken during SCADA implementation works. kVAmbewadi, 220 • 220 kVNagjheri - Kodasalli D/C and 220 kVHubli - Sirsi watchful of the prevailing grid conditions before scheduling/rescheduling of kVBidnal&220 KVHubli lines were kept open in the antecedent for operational purpose. generation at Nagjheri complex. 220 kVBidnal - Harti line-2 was in idle charged condition from KPTCL mail dated 28.01.2021: Bidnal end. ii. KPTCL to provide updated status of A/R of all 220kV lines at Nagjheri i. Communicated to CEE,SLDC - Completed • Initially three units were in service at Nagjheri with 400MW complex. ii. At Hubli and Bidnal Sub stations, KPTCL is ready for enabling AR for generation. As reported, under these conditions, Unit#4 at iii. KPCL to provide centralized DR downloading facility at their Nagjheri GS, Nagzari Connectted lines. Coordination required from KPCL. Confirmation Nagjheri was brought in, which resulted in overloading of the and sort out the issues in downloading DR’s from various protection relays at regarding readiness by KPCL for enabling AR for Hubli and Bidnal connected connected 220 kV lines and the lines tripped on overcurrent their Nagjheir GS. lines at Nagzari end is awaited. At Ambewadi Sub station, Circuit Breakers of protection. Nagzari lines have to be replaced, work is already taken up. Once Circuit Breaker • Running units at Nagjheri also tripped. These resulted in complete outage of 220 kV Nagjheri, 220kV Hubli, 220 kV replacement work is completed Ambewaadi end will be ready for enabling AR for Bidnal and 220 kV Ambewadi stations. Nagzari connected lines. - Pending
Page 12 of 52 Annexure-C 93/I/6 Complete outage of 230 kV 05-09-2020 at • Triggering incident was failure of Y ph CT of 230kV Hosur- i. TANTRANSCO to implement Main and Transfer bus or Double Bus scheme TANTRANSCO/ PGCIL (Sr-2) TANTRANSCO mail dated 18.01.2021: Pending Hosur SS of TANTRANSCO 01:19Hr. TN - Shoolagiri line-2. at 230/ 110kV Hosur_TN substation. Time synchronization of relays of the SS Will be ensured • Bus-1 BBP operated and all the elements connected to Bus-1 need to be ensured. tripped at 230 kV Hosur-TN end. ii. TANTRANSCO to submit detailed report regarding discrepancy pointed out • There was complete loss of supply at 230 kV Hosur-TN SS,since there is single bus operation at 230 kV Hosur-TN SS. in BBP operation and second B-E fault in 230kV Hosur_TN – Hosur_PG lines. Further, till numerical relays are provided for BBP protection, steps shall be taken to record BBP operation in line DRs. iii. TANTRANSCO to submit equipment failure report to CEA in respect of the failed Y-ph CT at 230kV Hosur_TN SS. iv. PGCIL-SR2 to submit a report regarding instantaneous tripping of 230kV Hosur-TN – Hosur PG line-2 at Hosur-PG end during second B-E fault during A/R dead time, in spite of detecting the fault in Zone-2 (carrier not received).
93/I/7 Complete outage of 220 kV 22-09-2020 at 13:05 • Triggering incident was tripping of 220 kVLingasugur - RTPS i. KPTCL to take up with Karnataka SLDC to ensure that necessary pre-emptive KPCL/ KPTCL KPCL mail dated 22.01.2021: Pending Lingasugur, 220 kV Bagewadi Hr. line-1 on distance protection due to fault in the line. After about steps such as reduction of RE generation on tripping of evacuating lines are ii) A/R is ready at RTPS end except sedam-1, Lingasugur-3. stations of KPTCL and 220 kV 4minutes, 220 kVLingasugur - Shahpura and 220 kVLingasugur taken in order to avoid cascade tripping of lines on overloading. Provision has been made for installation of Wave traps for the Sedam-1, Alamatti station of KPCL - RTPS line-2 tripped on overcurrent protection. ii. KPTCL and KPCL to enable A/R on all 220kV lines in RTPS-Lingasugur • As reported, after tripping of these lines, there was cascaded Lingasugur-3 under PSDF -II scheme & awaiting for approval from PSDF for tripping of the other 220 kV lines connected at Lingasugur complex. placing order on L1 bidder station, resulting in complete loss of supply at 220 kVLingasugur station. KPTCL mail dated 28.01.2021: • During the event, 220 kVBagewadi station and 220 kV i. Communicated to CEE,SLDC Alamatti station were also affected ii. At Lingasugur and Mallat end KPTCL is ready for enabling AR for RTPS connectted lines. Coordination required from KPCL. Confirmation regarding readiness by KPCL for enabling AR for Lingasugur and Mallat connected lines at Nagzari end is awaited.
93/II/1 Tripping of 400 kV Bus-2 at 400 03-08-2020 at 17:32 • During antecedent conditions, ICT#2 at Yelahanka was under i. PGCIL SR-2 to share the findings of the OEM on VFT over voltage referred to PGCIL(Sr-2)/ KPTCL KPTCL mail dated 28.01.2021: Pending kV Yelahanka SS of PGCIL-SR2 Hr. outage since 09:09Hr. due to AMP works. As per the and remedial measures thereof. ii. At Nelamangala Sub station, Settings for M-I and M-II relays of Yelahanka information received, while charging ICT#2 at 17:36Hr., Bus-2 ii. KPTCL to review & correct Zone settings on 400 kV Nelamangala – line are implemented considering protected line length as 38.9km. As per the BBP operated due to failure of R-phase bus isolator of ICT#2. Yelahanka line at Nelamangala end. • This resulted in the tripping of all the elements connected to discussion had during 93rd PCSC meeting, the actual length of this line is Bus-2 along with bus coupler. iii. KPTCL to ensure time synchronization of relays at Nelamangala SS. ascertained using offline fault locator. According to offline fault locator readings length of the protected line is 41.7km. In view of the above existing settigs at Nelamangala end is not reviewed. For taking further action in this regard, measurement of actual positive and zero sequence impedances of the line is envisaged. As test kit for measuring the sequence impedances of the lines is not available with KPTCL, assistance of Powergrid is requested by KPTCL.
93/V/1 Frequent Tripping of I. 220 Aug - September 220 kV Asupaka – Lower Sileru line tripped many times during i. APTRANSCO and TSTRANSCO to maintain proper right of way for the line APTRANSCO/ TSTRANSCO/ APGENCO Yet to be informed Pending kVAsupaka – Lower Sileru line 2020 August - September 2020. It has been reported that Auto by ensuring proper tree clearances. reclose function at 220 kV Lower Sileru is kept out of service ii. APGENCO to ensure DR time scale to be at least 2.5 sec to verify successful and same needs to be reviewed. Recurring non-operation of A/R. A/rand keeping A/r out of service may be elucidated by APTRANSCO/TSTRANSCO.
94/I/4 Complete outage of 220kV 31-Oct-20 Triggering incident was jumper cut in 220kV Jurala-Veltoor i. TSTRANSCO to correct sensitive earth fault settings on all 220 kV lines at all TSGENCO/ TSTRANSCO Yet to be informed Pending Lower Jurala GS of TSGENCO 04:23 hrs line. At the same time 220kV Lower Jurala- Veltoor, 220kV Stations in Jurala Complex (220 kV Upper Jurala GS, 220 kV Lower Jurala GS, Lower Jurala- Jurala lines-1, 2 & 3 tripped. Running units at 220 kV Jurala SS & 220 kV Veltoor SS) including providing directionality. Lower Jurala tripped due to loss of evacuating lines resulting in ii. TSGENCO to configure DR’s & EL’s of all protection relays at their 220 kV complete outage of Lower Jurala station. Lower Jurala GS for capturing all standard & requisite digital & analog signals.
94/I/14 Complete Outage of 400 kV 08-Dec-20 400kV NLC2 Expansion - NLC TS2 line was under outage For 400 kV Pugalur – NLC2Exp line, the following shall be carried out by PGCIL(Sr-2)/ NLCIL Yet to be informed Pending NLC2 Expansion 07:52 hrs during antecedent conditions due to CT and breaker failure at PGCIL-SR2 in coordination with NLCIL: NLC TS2 end. Triggering incident was tripping of 400kV i. End-to-end testing for DT/ permissive & other signals may be ensured by NLC2 Expansion -Pugalur line at Pugalur end on DT Receipt. testing at both the ends. Due to tripping of only connected 400kV line, there was complete loss of supply at 400kV NLC2 Expansion and this ii. Healthiness of PLCC system components (hardware and software) at both the resulted in a generation loss of 190MW. ends to be checked and faulty components to be repaired/ replaced.
Andhra Pradesh
92/III/3 Tripping of 220kV Asupaka - 09-06-2020 at 16:07 • Triggering incident was B-N fault in the line. At Asupka end, APGENCO to enable A/R at Lower Sileru end for the line. APGENCO Yet to be informed Pending Lower Sileru line-1 Hr. line tripped on operation of Zone-1 distance protection. • At Lower Sileru end, line tripped on operation of Zone-3 distance protection. • A/r not operated at both the ends.
Page 13 of 52 Annexure-C 84/II/9 Tripping of 220kV Bus 2 17-04-2019 at 5:40Triggering hr. incident was Y-phase to earth fault in 1. APTRANSCO to submit a detailed report regarding the subject tripping at APTRANSCO APTRANSCO mail dated 30.07.2019: Pending and connected elements at 220kV Gazuwaka Bus-2. This resulted in tripping of 220 kV Gazuawaka Substation along with the remedial measures taken. 1. The report submitted vide mail dated 29.07.2019 -- Completed 220kV Gazuawaka 220 kV elements and 400/220 kV ICT-2 2. For all lines emanating from Gazuwaka SS, RTV coating shall be taken up. 2. Pending Substation. APTRANSCO mail dated 03.10.2019 and 29.10.2019: 2).Tenders is under process for RTV coating of all the lines emanating from Vizag Switching Station.(VSS) -- Pending
86/I/3 Complete outage of 220 08-08-2019 at Triggering incident was failure of Y-ph LA of 220 1. APTRANSCO to submit equipment failure report to CEA,in respect of the APTRANSCO APTRANSCO mail dated 29.10.2019: Pending kV/132kV Paravada SS of 11:34 hrs kV Paravada- VSS (Vizag Switching Station) line at failed Lightning arrester, and to ensure healthiness of Lightning arresters in 1. Equipment failure report to CEA in respect of the failed Lightning arrester will APTRANSCO Paravada end. other phases. be sent soon, and healthiness of Lightning arresters in other phases are already 2. APTRANSCO shall also regularly perform third harmonic current checked on 08-08-2019. measurement (THRC) and measurement of LA stack temperature to monitor 2. Third harmonic current measurement (THRC) kit not available with healthiness of LA’s. APTRANSCO. Measurement of LA stack temperature to monitor healthiness of all LA’s is done every month along with other equipment and this month testing is scheduled on 02-11-2019 . --Completed
86/II/19 Tripping of 400 kV 5-08-2019 at Triggering incident was failure of R-phase LA in APTRANSCO to implement line differential protection for 400 kV Simhadri- APTRANSCO APTRANSCO mail dated 29.10.2019: Simhadiri-Kalpakka line- 13:37 hr. 400 kV Kalpakka-Asupaka line. Kalpakka line immediately and required OFC/OPGW may be arranged within a The line differential protection was enabled in 400 kV kalapaka 1,2&3; 400 kVKalpakka- week PGCIL(Gajuwaka) I & II feeders, 400 kV kalapaka HNPCL I & II feeders. LC Asupaka line-1 &400 was programmed on 15.10.2019, 17.10.2019 and 18.10.2019 for testing and kVKalpakka-Gazuwaka enabling the differential feature in 400 kV Kalapaka Simhadri-2,3, &, 4 feeders. line-2 clearance for testing was not accorded from M/s NTPC. As and when the clearance is accorded from M/s NTPC the differential feature will be enabled in 400 kv kalapaka Simhadri-2,3&4.
87/1/2 Complete Outage of 220 kV 28/08/2019 a. Bus-1 and Bus-2 Bus Bar Protection operated due to 1. APTRANSCO to investigate whether ageing or tension led to failure of R-Phase dropper from APTRANSCO APTRANSCO mail dated 25.02.2021: Pending Vizag Switching Station at 15:3 snapping of R-phase dropper jumper at 220 kV VSS r Jack bus to bridge which led to complete outage of 220 kV VSS and Parawada. 1. Pending and 220 kV Parawada SS of esulting in the tripping of all the connected elements. b. 400 2. Healthiness of other jumpers at 220 kV VSS shall be ensured and a report shall be furnished to 2. Thermovision scanning report furnsihed on 25.02.2021 - Completed kV/220 kV ICT#1 and 2 at Gazuwaka also got tripped during SRPC. APTRANSCO to submit Thermovision scanning reports of 220 kV VSS during past 6 APTRANSCO this event. months and ensure time sync at 220 kV VSS. c.220 kV Paravada SS was radially fed from 220 kV VSS during antecedent conditions.
87/III/3 Tripping of 400 kV 22-08-2019 at 4:00 B-phase to earth fault occurred in line. Auto-reclose was 1. APTRANSCO to submit a report after checking A/R operation. APTRANSCO Yet to be informed Pending Maheshwaram-Narnoor line hr. successful at Mahshwaram and A/R not operated at Narnoor 2. APTRANSCO to configure OVR start in EL.
88/1/4 Complete Loss of Supply at 29-11-2019 at Triggering incident was fault in 400kV Narnoor - APTRANSCO to ensure proper segregation of loads, generators and ICTs on both APTRANSCO Yet to be informed Pending 400/220kV Narnoor station 20:08 Hr. Srisailam line. LBB of Bus-1 operated and all buses in case of one and half breaker scheme while planning of substations elements connected to Bus-1 tripped. Since there was no other infeed to Narnoor station, there was complete loss of supply at 400/220kV Narnoor station. In the antecedent, Main breaker of 400kV Narnoor-Srisailam was in lockout condition and 220kV Narnoor -Somyzulpalli line-1 &2 was in idle charged condition.
88/II/19 Tripping of 400kV Kalpakka 28-10-2019 at 09:51 Triggering incident was R-N in the line. Fault was sensed in APTRANSCO to submit a report, after consultation with OEM, regarding the delay in tripping of APTRANSCO Yet to be informed Pending Vemagiri line-1 Hr. Zone-1 at both the ends. At both the ends A/R operated and line 400kV Kalpakka Vemagiri line-,1 inspite of the fault being detected in Zone-1. got tripped due to persistent fault. But at Kalpaka end, after A/R operation even though the fault was sensed in zone-1 there was delayed opening of all 3 ph breakers for around 250ms.
88/II/24 Tripping of 400/220kV ICT-1, 18-11-2019 at 21:54 Triggering incident was ICT-2, B-phase LA flashover. ICT -2 APTRANSCO to devise SPS scheme, designed to trip some loads in the event of tripping of any APTRANSCO Yet to be informed Pending ICT-2 and ICT-3 at Vemagiri Hr. tripped on differential protection and ICT-1 and ICT-3 tripped of the 400/ 220kV ICT’s at Vemagiri, to prevent cascaded tripping of all ICT’s due to overload in on over current protection. the event of outage of one ICT. ii. Also APTRANSCO to configure standalone EL with contacts wired from all static relays.
89/1/3 Complete outage of 220 kV 01-01-2020 at 11:40 • Bus bar protection operated resulting in complete outage of i. APTRANSCO to enable auto-reclosure in all lines emanating from 220 kv Bommuru SS. APTRANSCO Yet to be informed Pending Bommuru SS of APTRANSCO Hr. 220 kV Bommuru SS. ii. APTRANSCO to ensure time synchronization of relays with GPS at 220 kV Bommuru SS and 220 kV Vemagiri SS.
89/II/17 Tripping of 400 kV Vemagiri – 10-01-2020 at 13:59 • As reported, bus bar protection of 400 kV Bus-2 operated at APTRANSCO to expedite the process of replacing Static BBP at 400kV Vemagiri SS with APTRANSCO Yet to be informed Pending Sattenapally line of Hr. Vemagiri resulting in tripping of 400 kV Vemagiri – numerical BBP, to prevent mal-operations of BBP at Vemagiri SS. APTRANSCO Sattenapalli line.
90/III/2 Tripping of 400KV Vemagiri 10-01-2020 at 13:59 Triggering incident was R-N fault in the line. As per the report APTRANSCO to sort out time sync issue in 400KV Vemagiri (AP) - Simhadri- line-2. APTRANSCO Yet to be informed Pending (AP) - Simhadri-II Hr. submitted at Vemagiri end, it was mentioned that A/r operated and line tripped due to persistent fault. But from DR, it was observed that immediately after the opening of R pole, Y and B pole also got opened. As per the report submitted at Simhadri end, it was mentioned that A/r not operated due to receipt of DT from Vemagiri end. Non operation of A/r and sending of DT at Vemagiri end needs review. Page 14 of 52 Annexure-C 90/III/3 Tripping of 400kV Hinduja - KV 10-01-2020 at 13:59 Triggering incident was RN fault in the line. A/r not operated at APTRANSCO to check the reason for non-operation of A/R and time sync issue at KV Kota SS APTRANSCO Yet to be informed Pending Kota Line-2 Hr. KV Kota end due to carrier fail. At Hinduja end, A/r operated and furnish a report after testing. and line tripped due to persistent fault. Non operation of A/r at KV Kota end needs review.
90/III/15 Tripping of 400kV Hinduja KV 06-11-2019 at Triggering incident was R phase to Earth fault in the line. Fault • APTRANSCO to check the reason for non-operation of A/R at KV Kota SS and furnish a report APTRANSCO Yet to be informed Pending Kota line-1 11:33:00 Hr. was sensed in Zone-1 at both the ends. A/r operated successfully after testing. at HNPCL end and line was holding. At KV Kota end, A/r not operated and the same needs review.
91/I/12 Complete outage of 220kV 28-05-2020 at • Triggering incident was R-phase CT blast connected to 220kV APTRANSCO to ensure time synchronization of relays at 220kV Talapalli SS. APTRANSCO Yet to be informed Pending Talapalli SS of APTRANSCO 19:41Hrs side of 400/220kV ICT-2 at Talapalli. • Bus bar protection of both 220kV Bus-1 and Bus-2 operated and all connected elements tripped resulting in complete outage of 220kV Talapalli station.
91/II/9 Tripping of 400kV Vemagiri- 28-04-2020 at • Triggering incident was B N fault in the line. APTRANSCO to pursue rectification of the problem of Tie CB at Vemagiri for the subject line, in APTRANSCO Yet to be informed Pending Sattenapally line 16:42Hrs • A/r operated at both the ends and line tripped due to persistent consultation with OEM. fault. • At Vemagiri end, R and Y pole tie breaker didn't open immediately after A/r operation even though the fault was persistent. • Suspected opening of R and Y pole of tie breaker on PD operation. 91/II16 Complete outage of 220kV side 14-05-2020 at • As reported control cables caught fire at 220kV Vemagiri i. APTRANSCO to trigger DR and EL during BBP operation at 400/ 220kV Vemagiri SS. APTRANSCO Yet to be informed Pending of 400/220kV Vemagiri station of 00:40Hrs switchyard. ii. APTRANSCO to follow relevant standards, Regulations and guidelines to protect cable APTRANSCO • Bus bar protection of 220kV Bus-1 and Bus-2 operated trenches and to avoid cable damages due to fire. resulting in tripping of all connected elements. • 400/220kV ICT-1,2 and 3 also tripped.
91/II/17 Tripping of 220kV Bus-1 at 15-05-2020 at • Triggering incident was B-phase insulator disc flashover of i. APTRANSCO to perform stability check of BBP relays at Vemagiri SS. APTRANSCO Yet to be informed Pending 400/220kV Vemagiri station of 18:07Hrs 220kV Vemagiri - Bommuru line 2. ii. APTRANSCO to trigger DR and EL during BBP operation at 400/ 220kV Vemagiri SS. APTRANSCO • Bus bar protection of 220kV Bus-1 operated resulting in tripping of all elements connected to Bus-1.
91/III/10 Tripping of 400kV 22-04-2020 • Triggering incident was R-N fault in the line. Line tripped on APTRANSCO to disable A/R on the subject line at Narnoor end. On all lines emanating from APTRANSCO Yet to be informed Pending Narnoor – at 12:51Hrs Zone-1 distance protection. AR attempted at Narnoor end and Srisailam Left Bank, A/R shall be disabled at remote end. Srisailam LB line AR not attempted at Srisailam end.
92/II/8 Tripping of 220kV Bus-2 at 16-06-2020 at 02:20 • Triggering incident was Y-ph to ground fault in 220kV APTRANSCO to clear all debris/scraps from switchyard, to practice periodic thermal scanning APTRANSCO Yet to be informed Pending 400/220kV Vemagiri station Hr. Vemagiri - Bommuru Line-2. As reported, a creeper fell on Y- and adopt proper substation maintenance to avoid frequent BBP faults at 400/ 220kV Vemagiri Phase bus-2 Isolator dropper of the line. SS. • Bus bar protection of 220kV Bus-2 operated and all elements connected to the bus tripped.
92/II/11 Tripping of 220kV Bus-1 at 20-06-2020 at 06:22 • Triggering incident was B-ph to ground fault in 220kV APTRANSCO to clear all debris/scraps from switchyard, to practice periodic thermal scanning APTRANSCO Yet to be informed Pending 400/220kV Vemagiri station Hr Vemagiri - Vijjeswaram feeder. As reported, an aluminium lead and adopt proper substation maintenance to avoid frequent BBP faults at 400/ 220kV Vemagiri fell on B-Phase, Bus-1 isolator dropper connected to 220KV SS. Vijeswaram feeder. • Bus bar protection of 220kV Bus-1 operated and all elements connected to the bus tripped
92/II/12 Tripping of 400kV Uravakonda- 24-06-2020 at 15:55 • Line tripped only at Talaricheruvu end on operation of 86A & APTRANSCO to resolve in PSL logic issue at Talarichevu end relay of the line at the earliest to APTRANSCO Yet to be informed Pending Talarichevu line-2 Hr. 86B relays due to wrong configuration in PSL logic during avoid unwanted tripping of the line to facilitate RE evacuation. carrier failure condition. • It was also reported that there was Channel-1 failure momentarily for 2-3s.
92/IV/6 Tripping of 400kV Kalpakka - 24-07-2020 at 11:41 • Line tripped (only) at Kalpakka end on DT Receipt, due to APTRANSCO to check the PLCC equipment of the line and rectify the problem of PLCC APTRANSCO Yet to be informed Pending Gazuwaka line-1 and 2 Hr. suspected maloperation of PLCC. maloperation.
93/I/1 Complete outage of 220/132 kV 02-08-2020 at 03:46 • Triggering incident was current spike detected in 220 i. APTRANSCO to implement multiple bus operation (Main and transfer bus or double bus APTRANSCO Yet to be informed Pending Chittoor station of APTRANSCO Hr. kVKalikiri feeder due to suspected problem in CB interruption scheme) at their 220/132kV Chittoor substation. 09-08-2020 at 09:02 circuit. ii. APTRANSCO to ensure GPS time synchronization of all relays at their 220/ 132 kV Chittoor Hr. • It is reported that current detected was in the range of 14.5kA. SS. 09-08-2020 at 10:46 This led to the operation of bus bar protection of 220/132 Hr. kVChittoor bus and all connected elements at 220 kVChittoor tripped. • 220 KVChittoor station has single bus configuration. 132 kVChittoor was also affected since it is radially connected.
Page 15 of 52 Annexure-C 93/I/8 Complete outage of 220 kV 25-09-2020 at 15:46 • Triggering incident was fault in both the connected lines, viz. i. APTRANSCO to provide centralized DR facility at their 220 kV Duvva SS. APTRANSCO Yet to be informed Pending Duvva station of APTRANSCO Hr. 220 kV Duvva - Bheemavaram and 220 kV Duvva - Vemagiri Ii. APTRANSCO to ensure time synchronization of all relays at 220kV Duvva SS. at 220 kV Duvva station. • This resulted in complete loss of supply at 220 kV Duvva station.
94/II/19 Tripping of 400kV Kalpaka- 13-Nov-20 As per the report submitted, triggering incident was fault in i. APTRANSCO in coordination with PGCIL-SR-1 to resolve the spurious tripping of 400kV APTRANSCO Yet to be informed Pending Gazuwaka Line-1 11:12 hrs 400kV KV Kota - Hinduja line-2. 400kV Kalpakka - Kalpakka - Gazuwaka Line-1 on SOTF protection during the tripping of 400kV HNPCL- KV Gazuwaka line tripped only at Gazuwaka end due to suspected Kota line-2 including replacing the concerned line protection replays, P546. 16-Nov-20 mal operation of Main-2 (Schneider make P546 type) SoTF ii. APTRANSCO to maintain proper ROW for 400kV HNPCL- KV Kota lines to avoid frequent 12:17 hrs function and the same needs review. faults on the line.
Page 16 of 52 Annexure-C
Telangana
82/II/1 Tripping of 400kV KTPS 05-01-2019 Line tripped at KTPS VI end due to suspected mal- 1) TSGENCO to configure OVR_start and OVR_tripin EL at KTPS-VI end and TSGENCO TSGENCO mail dated 24.06.2019: Pending OVR_start and OVR-trip configured VI- KTPS VII at 10:17hrs operation of over-voltage protection. Line was in sent a report after completion of works related to DT communication channel The issue is referred to M/s BHEL ( EPC vendor ) and the study on feasibility in EL at KTPS VI ? service from KTPS VII., BUS CVT secondary R between KTPS-VI and KTPS-VII for providing the communication with the existing available system is under PHASE got grounded at KTPS VI process and will be completed during the availability of next shutdown.
Review meeting on 27.06.2019: TSGENCO informed that the recommendations will be completed in September 2019
TSGENCO mail dated 10.02.2020: DT communication between KTPS-VI stage and KTPS-VII stage has been provided on 09.08.2019. Hence, it is requested to drop the point,
83/III/6 Tripping of 400kV 14-03-2019 at Triggering incident was R-ph fault in the line. At It was noted that no representative of TSGENCO attended the meeting. TSGENCO TSGENCO mail dated 24.06.2019: Pending Julurpadu - Manuguru line- 06:10:00 Julurpadu end, fault was sensed in Zone-2 and TSGENCO is recommended to submit a report on the tripping and to furnish FIR, DR and EL was uploaded in SRLDC website.Trip Report was also 2 carrier was received but due to DT Receive from equipment failure report to CEA. submitted. manuguru end, A/r not operated and line got tripped. FIR, DR and EL of Manuguru end are not Review meeting on 27.06.2019: available. TSGENCO informed that Equipment failure report will be sent to CEA.
84/II/28 Frequent tripping of 220 05-04-2019 at In 155thOCC meeting of SRPC, APTRANSCO 1. TSGENCO to check the non-operation of carrier aided trip, when fault is TSGENCO Yet to be informed Pending kV KTPS –Nunna line 12:55 hr. B-N informed that the tripping was due to clearance detected at KTPS end in Z-2 and carrier is also received, and submit a report FAULT issues in the ROW caused by mango tree. It was regarding the same. 15-04-2019 at cleared and issue was rectified. However, frequent 2. TSGENCO and APTRANSCO to ensure that ROW is cleared periodically. 13:20 hr. Y-N tripping of line is still persistent. 3.APTRANSCO & TSGENCO may consider raising the height of towers if the FAULT line is planned to be used in future. 16-04-2019 at 4.TSGENCO to consider replacement of old pneumatic CB’s at KTPS if 220kV 88/II/3 Tripping of 220kV KTPS-Nunna 27-09-2019 at 14:41 · Line tripped at Nunna end only on operation of Zone-2 TSGENCO to verify the relay DRs and EL corresponding to the event and submit a report to TSGENCO Yet to be informed Pending Hr. distance protection. SRPC regarding the event. · It was further mentioned in the report that there was bus fault at KTPS end. • Non operation of protection at KTPS end needs review
92/IV/4 Tripping of 400KV Julurpadu - 10-07-2020 at 16:46 • Line tripped on only at Julurpadu end on DT Receipt, due to TSGENCO to sort out the issue with PLCC maloperation in consultation with OEM. TSGENCO Yet to be informed Pending Manuguru Ckt-2 Hr. suspected maloperation of PLCC.
93/I/4 Complete outage of 400 kV 20-08-2020 at 22:25 • As reported, fire broke out at 400 kVSrisailam LB station of TSGENCO to submit a detailed report and suggestions of their technical enquiry committee for TSGENCO Yet to be informed Pending Srisailam Generating Station Hr TSGENCO. All running units at Srisailam LB tripped one after information and discussion in the PCSC forum. (SLB) of TSGENCO another. • All connected lines at Srisailam LB station tripped at remote end on Zone-2, distance protection and DT also received. • Oscillations were also observed from 22:24 Hr. to 22:46 Hr. in Southern Region during the event. Oscillations died out after tripping of all the running units at Srisailam LB
93/V/2 Frequent tripping of 220 kV August - September 220 kVChilakallu - Pulichinthala line tripped a number of times TSGENCO to enable A/R at Pulichinthala SS at the earliest and to take care of the following at TSGENCO Yet to be informed Pending Chilakallu - Pulichinthala line 2020 during August - September 2020. It was informed in PCSC-92 Pulichinthala end: that A/R is yet to be put in service at Pulichinthala end. a. Zone pick up to be configured in DR and EL. b. DR time scale to be increased to atleast 2.5 sec. c. To ensure time sync of relays.
93/V/3 Frequent tripping of 220 kV August - September 220 kV KTPS - Nunna line tripped many times during August - TSGENCO to enable A/R at KTPS end for the KTPS - Nunna line. TSGENCO Yet to be informed Pending KTPS - Nunna line 2021 September 2020. A/R is not enabled at KTPS end.
94/II/20 Tripping of 220 kV Bus-1 at 16-Nov-20 Triggering incident was failure of CB of U#5 at Srisailam RB. TSGENCO to submit a report detailing the following, along with remedial action taken: TSGENCO Yet to be informed Pending Srisailam Right Bank of 20:26 hrs LBB operated resulting in the tripping of all the elements i. LBB operation on account of the failure of R-ph limb of CB of Unit-5 and consequent tripping APGENCO connected to Bus-1 at Srisailam RB. There was no generation at of all 220 kV Bus-I connected elements Srisailam LB during antecedent conditions. ii. Tripping of 220kV Srisailam RB – Nagarjunasagar_TS line from Nagarjunasagar_TS end during above incident.
Page 17 of 52 Annexure-C 84/II/27 Multiple tripping at 220 kV 27-05-2019 at Triggering incident was failure of B-phase CT of 1.TSTRANSCO is recommended to submit Equipment failure report to CEA TSTRANSCO TSTRANSCO MAIL DATED30.10.2019: Pending Ghanapur station 02:04 hr. bus coupler of Bus-2. Bus bar protection of 220 kV regarding the blast CT. 1. Informed our transmission wing to submit the Equipment failure report to Bus-2 operated resulting in tripping of all elements 2.TSTRANSCO to inform if any old CTs exist in Ghanapur SS and ensure CEA. connected to Bus-2. healthiness of the same to 2. All the existing old CTs are replaced with new one.
89/II/8 Tripping of Bus-2 at 220 kV 21-12-2019 at 03:10 • Triggering incident was B-N fault in 220 kV Malyalapalli- TSTRANSCO to ensure A/R functionality on all lines emanating from 220 kV TSTRANSCO TSTRANSCO mail dated 28.11.2020: Pending Malyalappali (Ramagundam) Hr. Ramapur line. Malyalapalli SS and to ensure time synchronization of relays between Rampur Time synchronization is done. PLCC panel erection for Rampur feeder is under station. • LBB of Bus-2 operated since B-phase CB of 220 kV and Malyalapalli. progress. Malyalappali-Ramapur line did not open due of damage in trip coil
91/II/18 Tripping of 400kV DICHPALLY 22-05-2020 at • Line tripped on operation of overvoltage stage-1 protection at TSTRANSCO to check the transient performance of CVTs at Dichipalli SS. TSTRANSCO TSTRANSCO mail dated 28.11.2020: Pending - NIRMAL line-2 07:12Hrs Dichipally end and DT received at Nirmal end. Issue with the neutral links provided in the CVT MB for connecting the CVT • From the Dichipally end DR, R-phase voltage is observed to core neutral earthing suspected. Intimated the MRT wing to check with the be much higher than the other two phase voltages. neutral links in the CVT MBs.
93/III/3 Tripping of 400 kV Khammam- 03-09-2020 at 08:48 • Triggering incident was B-N fault in the line. At Khammam TSTRANSCO to rectify the persisting carrier failure alarm at Asupaka end of TSTRANSCO Yet to be informed Pending Asupaka Line-1 Hr. end, line tripped on Zone-2 distance protection due to non- the Khammam-Asupaka Line-1 by mid December 2020 and enable A/R. receipt of carrier. • At Asupaka end, line tripped on operation of Zone-1 distance protection and A/r not operated due to carrier failure
93/III/4 Tripping of Jangaon - Tippapur 13-09-2020 at 04:38 • Triggering incident was R-N fault in the line. Line tripped on TSTRANSCO to sort out the issues in autoreclosure for the line by 15 December TSTRANSCO Yet to be informed Pending line-1 Hr. Zone-1 distance protection at both ends. 2020. • AR not operated at both ends.
94/II/30 Multiple Trippings in 400kV 02-Dec-20 As per the report submitted, triggering incident was Y-E fault in TSTRANSCO to modify SOTF logic at Gajwel and ensure that SOTF TSTRANSCO Yet to be informed Pending Gajwel SS of TSTRANSCO 03:07 hrs 400kV Gajwel-Narsapur line -1. Fault was sensed in zone-1 protection takes breaker status as input and only during change in breaker status protection at Narsapur end and carrier aided Zone-2 protection from Open to close, it would sense current and operate in case of fault. operated at Gajwel end. A/R operated and successful at both the ends. At the same time, 400KV Gajwel-Chandulapur-2 line tripped at Gajwel end only on suspected maloperation of SOTF and the same needs review.
Karnataka
46/II/21 Trippings at 220kV Raichur 07-06-2015 at 1. KPCL to check the operation of anti-pumping relay on 220 kV side and keep KPCL Mail received on 21-10-2015: Pending TPS 01:35 hrs it in healthy condition. 1) Anti-pumping contactors of all the nine 220KV Lines are in circuit and tested periodically during AOH works of lines along with other protections. 2. KPCL to provide manual reset to the 220 kV side master trip relay. 2) Completed. 3) Possibility to use both the 220kV buses as main bus under normal operation is 3. KPCL to use both the 220 kV buses as main buses under normal operation, under review. and should go for single bus operation only during emergencies. Mail recieved on 23-11-2015: 1) Completed 3) Two bus operation for 220kV buses : In place of existing CT switching relays, High speed manual heavy duty change over switch of sufficient current capacity will be retrofitted to all feeders at 220kV station and same will be operated manually during changeover of feeder by one bus to the other and this arrangement may facilitate to put both buses in service. Time required for this retrofit is around 90days . However, this work will be taken up only after retrofitting of electromagnetic relays with numerical relays for Main-2 protection of all 220kV lines, for which work is in progress. Status received vide mail dated 10-07-2017: 1) --- Completed. 2) --- Completed. 3) Two Bus operation for 220kV bus is being carried out whenever required. However scheme for tripping of one bus during LBB/fault and maintaining the other bus intact by tripping B/C breaker will be taken up in R&M works. ---
Page 18 of 52 46/II/21 Trippings at 220kV Raichur 07-06-2015 at 1. KPCL to check the operation of anti-pumping relay on 220 kV side and keep KPCL Pending TPS 01:35 hrs it in healthy condition.
2. KPCL to provide manual reset to the 220 kV side master trip relay.
3. KPCL to use both the 220 kV buses as main buses under normal operation, and should go for single bus operation only during emergencies.
Annexure-C Status received vide KPCL mail dated 14.12.2017: 3) DPR for implementation of Two Bus operation for 220kV bus system has been prepared and proposal is placed for funds from PSDF. After the approval of the DPR, the work is proposed to be taken up.
Review Meeting dated 19.12.2017: 3) KPCL informed that DPR for implementation of Two Bus operation for 220kV bus system has been prepared and proposal is placed for funds from PSDF. After the approval of the DPR, the work is proposed to be taken up. Time frame requested for is 2 yrs.
KPCL mail dated 19.12.2018: 3) Work proposed to be taken up under PSDF. Approval from Nodal agency is awaited. However, arrangements have been made to issue NIT.
Review Meeting on 21.12.2018: KPCL informed that Tender would be floated in 1 month and work would be completed in 2 years.
KPCL mail dated 23.03.2019: Arrangements have been made to issue NIT and Tender for the work proposed to be floated during May- 2019. KPCL mail dated 10.05.2019: NIT will be issued during May- 2019. KPCL mail dated 25.06.2019: 1. & 2. Completed 3) Preparation of technical specification is in progress. NIT will be issued during July- 2019. Review meeting on 27.06.2019: KPCL informed that timeline for completion of work is December 2019.
KPCL mail dated 16.07.2019: 1. & 2. Completed 3) Preparation of technical specification is in progress. NIT will be issued during July- 2019. timeline for completion of work is December 2019.
KPCL mail dated 30.10.2019 and 17.12.2019 and 11.02.2020: 1. & 2. Completed 3) NIT issued during Aug- 2019. Timeline for completion of work is December 2020.
KPCL mail dated 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: 1. & 2. Completed 3) NIT issued during Aug- 2019. Tender evaluation is completed. Awaiting approval from PSDF for placing PO on L1 agency.
54/II/9 Tripping of 400kV Raichur 13-04-2016 at Y-ph Pole of Tie-breaker of Unit-4 at RTPS failed. 1.KPCL to undertake the following remedial measures to avoid breaker KPCL Status received vide KPCL mail dated 10.07.2017: Pending TPS 21:12 hrs Unit-4 got tripped on operation of Generator flashovers: 1. (ii) Hot line water washing stopped and off line water washing is carried out Bus-2 Differential, Reverse power & LBB protection. (i) Replacing all porcelain insulators with composite insulators whenever the 400 KV Unit or line is under tripped condition / Shutdown Operation of LBB protection led to tripping of BUS- (ii) Carrying out hot-line water washing of all insulators on regular basis. condition. --- Completed 2 at RTPS (iii) Applying Room Temperature Vulcanizing (RTV) Silicone high voltage 1. (iii) Silicon coating for Unit#8 main & tie breakers carried out in Sep'16 and insulator coatings to all bus-connected ceramic insulators of equipment like CT, same is under observation. Till today in order and good condition. For remaining PT, CB, Isolators etc. breakers, since it is big order, approval for the same is under process. --- Review Meeting dated 19.12.2017: 2.KPCL to take steps to provide dedicated breaker flashover protection to all 1 (iii) As upgradation of 400kV switchyard equip's to be taken under PSDF breakers at Raichur TPS at the earliest. funds, Silicon rubber coating for breakers is deffered till then. --- Pending
2. Replacement by Num relay for Units - 5,6 & 7 completed in the month of Oct- 2017. Main-I is Seimens make and Main-II is ABB make. --- Pending
KPCL mail dated 19.01.2018: 2. Replacement of Numerical relays for Units-5, 6 & 7 have been completed. Referred to OEM for providing the Breaker flashover protection for all the breakers.
KPCL mail dated 19.12.2018: 2. Reply is awaited from OEM of Numerical relays for providing Breaker Flashover protection for all the breakers --- Pending
Review Meeting on 21.12.2018: 1. KPCL assured that porcelain insulator replacement will be taken care in tender floated for RTPS Busbar modification --- Pending
KPCL mail dated 23.01.2019: 1) i) Being discussed with other utilitis. 2) Reply is awaiting from OEM to implement the Breaker flash over protection in KPCL mail dated 23.03.2019: 1) (i) & (iii)- Arrangements have been made to issue NIT and Tender for the work proposed to be floated during May- 2019.
2) Reply is awaiting from OEM to implement the Breaker flash over protection in the Numerical relays in 400KV station. & Being discussed with other utilities. It is requested to furnish Necessary logic and settings to implement the breaker flashover protection
KPCL mail dated 10.05.2019: 1) (i) & (iii)- NIT floated on 01.03.2019
2) Reply is awaiting from OEM to implement the Breaker flash over protection in
Page 19 of 52 54/II/9 Tripping of 400kV Raichur 13-04-2016 at Y-ph Pole of Tie-breaker of Unit-4 at RTPS failed. 1.KPCL to undertake the following remedial measures to avoid breaker KPCL Pending TPS 21:12 hrs Unit-4 got tripped on operation of Generator flashovers: Bus-2 Differential, Reverse power & LBB protection. (i) Replacing all porcelain insulators with composite insulators Operation of LBB protection led to tripping of BUS- (ii) Carrying out hot-line water washing of all insulators on regular basis. 2 at RTPS (iii) Applying Room Temperature Vulcanizing (RTV) Silicone high voltage insulator coatings to all bus-connected ceramic insulators of equipment like CT, PT, CB, Isolators etc.
2.KPCL to take steps to provide dedicated breaker flashover protection to all breakers at Raichur TPS at the earliest.
Annexure-C Review meeting on 27.06.2019: SRPC informed that referenc of necessary logic and settings to implement the breaker flashover protection will be shared soon.
KPCL mail dated 16.07.2019: 1) (i) & (iii)- NIT floated on 01.03.2019. Cover-I opened. Technical evaluation is in progress. Approval from Nodal Agency for PSDF funds is awaited. 2) As confirmed during 84th PCSC meeting, SRPC may suggest/furnish referenc of necessary logic and settings to implement the breaker flashover protection. reply in this regard is awaited.
KPCL mail dated 30.10.2019 and 17.12.2019 and 11.02.2020 & 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: 1) (i) & (iii)- NIT floated on 01.03.2019. Tender evaluation is completed. Approval from Nodal Agency for PSDF funds is awaited for placing PO on L1 agency. 2) As confirmed during 84th PCSC meeting, SRPC may suggest/furnish referenc of necessary logic and settings to implement the breaker flashover protection. reply in this regard is awaited.
Page 20 of 52 Annexure-C 54/II/13 Tripping of Units at 220 kV 15-04-2016 at During testing of retrofitted distance protection in In view of the availability of two buses along with healthy bus-coupler at 220 KPCL Status received vide KPCL mail dated 10.07.2017 & 14.12.2017: Pending Timeline? Raichur TPS 15:36 hrs 400kV Raichur-2 feeder, LBB protection trip DC kV RTPS, KPCL is recommended to put in service the double-bus operation at Two Bus operation for 220kV bus is being carried out whenever required. got extended to Bus trip. This resulted in tripping of 220 kV RTPS by suitably distributing loads within 15 days. However scheme for tripping of one bus during LBB/fault and maintaining the 220kV bus at RTPS and all connected 220 kV other bus intact by tripping B/C breaker will be taken up in R&M works. elements. Unit-4 which is connected to 400 kV Bus got tripped due to tripping of Station Utility Review Meeting dated 19.12.2017: Transformer that is connected 220 kV bus 3) KPCL informed that DPR for implementation of Two Bus operation for 220kV bus system has been prepared and proposal is placed for funds from PSDF. After the approval of the DPR, the work is proposed to be taken up. Time frame requested is 2 yrs.
KPCL mail dated 20.12.2018 & 23.01.2019: Work proposed to be taken up under PSDF. Approval from Nodal agency is awaited. However, arrangements have been made to issue NIT.
KPCL mail dated 10.05.2019: NIT will be issued during May- 2019.
KPCL mail dated 25.06.2019: Preparation of technical specification is in progress. NIT will be issued during June/July- 2019.
Review meeting on 27.06.2019: KPCL mail dated 16.07.2019 & 30.10.2019: NIT will be issued during July- 2019. Time line for completion of work is Dec- 2020.
KPCL mail dated 17.12.2019 and 11.02.2020 : NIT issued during Aug-2019. Time line for completion of work is Dec-2020.
KPCL mail dated 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: NIT issued during Aug- 2019. Tender evaluation is completed. Awaiting approval from PSDF for placing PO on L1 agency.
Page 21 of 52 Annexure-C 58/I/3 Complete outage of 220 kV 06-09-2016 LBB of 220kV Kodasalli breaker at Kadra end got 1) KPCL to check settings of LBB protection in all relays from which it was KPCL Status received vide KPCL mail dated 14.06.2017: Pending (GD) Kadra power station of at 14:40 hrs operated which resulted in tripping of Bus at Kadra implemented, and ensure that their configuration, logic, and timing are in order 1. All logics checked and found normal. LBB timing checked and found 200msec KPCL and in turn led to tripping of all elements at their 220 kV Kadra PH. as per KPTCL MRT recommendation. - Completed 2. Work Under Progress ---- Pending 2) KPCL to furnish details regarding the existing LT auxiliary supply 3. New GPS System commissioned along with new numerical and synchronised arrangement at their 220 kV Kadra PH, and take steps to provide a suitable Auto- with GPS system - Complied Main-Fail (AMF) panel for DG set to effect its auto-starting in case of failure of 4. Work Under Progress ---- Pending LT supply. Status received vide mail dated 14.12.2017: 1),3),4) Completed 3) KPCL to ensure time-sync of all relays (DR’s & EL’s) with GPS at their 220 2. Auto Start of DG set is taken up --- Pending kV Kadra PH. Review Meeting dated 19.12.2017: 4) KPCL to provide stand-alone Event Logger at their 220 kV Nagjheri PH. 2. KPCL informed that for AMF of DG, Scheme prepared & material procurement under process. The AMF scheme will be implemented in January 2018. --- Pending 3. The GPS system commissioned on Nov 2016 & all the numarical relay time synchronised with GPS ---- Completed
Review Meeting on 21.12.2018: KPCL informed that Tender for the work would be floated by January 2019 and work would be completed in 1 year.
KPCL mail dated 23.01.2019: 1) Completed. 2) Tender for the work would be floated by February 2019 and work would be completed in 1 year....Pending 3) Completed. 4) Tender for the work would be floated by Feb, 2019, and work would be completed in 1 year....Pending
KPCL mail dated 23.03.2019: 2) Tender for the work proposed to be floated during May- 2019 after model code of conduct and work would be completed in 1 year . 4) Tender for the work proposed to be floated during May- 2019 after model code of conduct and and work would be completed in 1 year.
KPCL mail dated 10.05.2019: Tender will be floated during 3rd week of May- 2019.
KPCL mail dated 25.06.2019: 1 & 3) Completed. Review meeting on 27.06.2019: .1 & 3) Completed. 4) Tender published on 21.06.2019 and time line in June 2020. 2. tender has to be issued. Timeline requested upto December 2020.
KPCL mail dated 16.07.2019 : 1 & 3) Completed. 2 ) NIT will be issued during Aug-2019. 4) Tender published on 21.06.2019. Time line for completion of Work is Dec- 2020.
KPCL mail dated 30.10.2019 and 17.12.2019: 1 & 3) Completed. 2 ) NIT issued during Sept-2019. 4) Tender published on 21.06.2019. Time line for completion of Work is Dec- 2020.
KPCL mail dated 11.02.2020: 1 & 3) Completed. 2 ) NIT issued during Sept-2019. Tender evaluation is inprogress. 4) As per the directions of TESG of NLDC i..e. Numerical relays are being provided for all Units and Lines, the proposal of providing Disturbance recorder is excluded from DPR submitted for availing funds from PSDF - Issue may be dropped. --- Dropped
KPCL mail dated 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: 1 & 3) Completed. 2 ) NIT issued during Sept-2019 and resulted in receipt of single qualified bidder in Cover-1. Hence, tender refloated for Call-2 on April 2020. Evaluation is under progress 4) Dropped.
Page 22 of 52 Annexure-C 69/II/8 Tripping of 220 kV Kaiga- 06-10-2017 at While de-synchronising of Unit-2, B-phase pole of KPCL to take steps to replace the existing static protection relays for Generator KPCL Status received vide mail dated 25.07.2018: Pending Kadra line-1 22:22 hrs GCB did not open and pole descrepancy relay Units and Generating Transformers (GT’s) with suitable Numerical relays at Numerical Generator protection relay replacement proposed to be taken up operated. Hence all 220KV lines CB hand tripped. their 220 kV Kadra PH. alongwith SCADA work. KPCL mail dated 20.12.2018: Will be taken up along with SCADA work. NIT to be issued on Jan-2019 Review Meeting on 21.12.2018: KPCL informed that Tender for the work would be floated by March, 2019, and work would be completed in 1 year. KPCL mail dated 23.01.2019: Tender for the work would be floated by February-2019 and work would be completed in 1 year.
KPCL mail dated 23.03.2019: Tender for the work proposed to be floated during May- 2019 after model code of conduct and work would be completed in 1 year
KPCL mail dated 10.05.2019: Tender will be floated during 3rd week of May- 2019.
KPCL mail dated 25.06.2019: Tender published on 21.06.2019.
Review meeting on 27.06.2019: KPCL mail dated 16.07.2019: Tender published on 21.06.2019. Time line for completion of Work is Dec-2020.
KPCL mail dated 30.10.2019 and 17.12.2019 and 11.02.2020: Tender published on 21.06.2019. No bids received for the tender. Hence, it is proposed to refloat fresh tender with revised PQR and scope of work. Avaialing approval in this regard is in progress.
KPCL mail dated 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: Preparation of estimate and technical specification is in progress..
72/I/4 Complete outage of 220kV 01-02-2018 High resistance fault occurred in 110kV Sedam- KPCL to disable GFC protection on all lines emanating from their generating KPCL Review Meeting on 21.12.2018 Pending Sedam, Shahapur, at 17:46 hrs Chittapur line near Sedam end. Line DEF operated stations. KPCL informed that compliance w.r.t. Implementing the recommendation would Shahabad, Kapanoor, and backup OC protection of 100MVA transformer be furnished soon. Humnabad and Halabarga operated at Sedam end. But line breaker and KPCL mail dated 23.03.2019: Stations of KPTCL transformer HV breaker didn’t open due to problem 'GFC protection will be disabled in all lines in coordination with M/s.KPTCL in trip circuit. This resulted in cascade tripping of upstream feeders and power supply was lost to six KPCL mail dated 10.05.2019 & 25.06.2019 & 16.07.2019 & 30.10.2019 & 220kV stations of KPTCL. 17.12.2019 & 11.02.2020: Letter addressed to CE, RT, KPTCL dated: 10.04.2019 to disable GFC protection in all 220kV lines . Reply is awaited.
KPCL mail dated 21.05.2020 & 28.09.2020 & 26.11.2020: Letter dated: 28.04.2020 addressed to CE, RT, KPTCL to disable GFC protection in all 220kV lines . Reply is awaited.
KPCL mail dated 22.01.2021: Letter dated: 28.04.2020 addressed to CE, RT, KPTCL to disable GFC protection in all 220kV lines . Reply is awaited.Reminder letters dated:16.06.2020, 27.08.2020 has been also addressed to CE, RT, KPTCL to disable GFC protection in all 220kV lines. Reply is awaited.
73/I/5 Complete outage of 220kV 15-03-2018 at There was Y-phase to ground fault on 220 kV KPCL to take steps to put double-bus operation into service at their 220 kV KPCL Status received vide mail dated 25.07.2018: Pending Varahi power station 22:36 hrs Varahi - Shimoga line-2. Consequent to persisting Varahi PH. Under Implementation. fault in ‘Y’ phase, the breaker failure protection operated resulting in operation of 220KV bus bar KPCL mail dated 20.12.2018 & 23.01.2019 & 23.03.2019: protection at Varahi, tripping all the connected lines Retrofitting of 220kV Bus Isolators is under progress. Proposed to be in service and Varahi running units. after April-2019
KPCL mail dated 10.05.2019: 4 Set of Isolators of VS1, VS2 & VM2 bay of North Bus were cmpleted. Remaining bays will be completed after Concurrence of LC from LDC
KPCL mail dated 25.06.2019 & 16.07.2019 & 30.10.2019: 4 Set of Isolators of VS1, VS2 & VM2 bay of North Bus were cmpleted. Remaining bay will be completed after monsoon season i.e during November - 2019
KPCL mail dated 17.12.2019 and 11.02.2020 & 21.05.2020 & 27.07.2020 & 27.07.2020 & 28.09.2020:: 4 Set of Isolators of VS1, VS2 & VM2 bay of North Bus were cmpleted. Several times LC is requested for carrying out work for remaining bay. However, LC is awaited from SLDC.
KPCL mail dated 26.11.2020 & 22.01.2021: Isolators of all Lines & Bus coupler bay of North Bus were completed. Availing approval for procurement of Isolators for remaning bays is in progress.
Page 23 of 52 Annexure-C 78/I/1 Complete Outage of 220 kV 24-08-2018 at Due to suspected mal-operation of 220KV bus bar 1. KPCL to take steps to put double-bus operation into service at their 220 kV KPCL KPCL mail dated 20.12.2018 & 23.01.2019: Pending Varahi UGPH. 11:00 hrs protection at Varahi, all the connected lines and Varahi UGPH by December, 2018. 1. Retrofitting of 220kV Bus Isolators is under progress. Proposed to be in service Varahi running Units got tripped. (6 nos 220kV after April-2019 --- Pending lines and 4 nos Varahi generating station running 2. KPCL to employ correct operational practices like keeping DC fuses of B/C 2. ---- Completed. Units). This resulted in complete outage of 220kV CB intact during bus changeover works, disabling back-up protections of B/C KPCL mail dated 23.03.2019: Varahi UGPH CB during bus changeover works & enabling them with proper settings only 1) Retrofitting of 220kV Bus Isolators is under progress. Proposed to be in when it is used as Main-CB of the grid elements. service after April-2019
KPCL mail dated 10.05.2019: 4 Set of Isolators of VS1, VS2 & VM2 bay of North Bus were cmpleted. Remaining bays will be completed after Concurrence of LC from LDC.
KPCL mail dated 25.06.2019 & 16.07.2019 & 30.10.2019: 4 Set of Isolators of VS1, VS2 & VM2 bay of North Bus were cmpleted. Remaining bay will be completed after monsoon season i.e during November - 2019
KPCL mail dated 17.12.2019 and 11.02.2020 & 21.05.2020 & 27.07.2020 & 28.09.2020: 4 Set of Isolators of VS1, VS2 & VM2 bay of North Bus were cmpleted. Several times LC is requested for carrying out work for remaining bay. However, LC is awaited from SLDC.
KPCL mail dated 26.11.2020 & 22.01.2021: Isolators of all Lines & Bus coupler bay of North Bus were completed. Availing approval for procurement of Isolators for remaning bays is in progress.
87/I/3 Complete Outage of 220kV 29-09-2019 at 11:31 a. Single line to ground fault occurred in 220kV Kemar – KPCL to check A/R functionality for all lines emanating from 220 kV Varahi GS and submit a KPCL KPCL mail dated 27.07.2020: Pending Kemar, MSEZ, hrs Varahi line-2 due to R-phase insulator flashover and the line report regarding the same. It will be intimated shortly. Puttur&Kavoor stations of tripped on Zone-1 distance protection. Simultaneously, 220kV Kemar – Varahi line-1 tripped at Kemar end only. KPCL mail dated 28.09.2020: KPTCL b. 220kV Kemar –Varahi line-3 tripped due to overloading. During this fault , AR is temporarily kept OFF conditions, due to the wave trap fall down during This resulted in complete loss of supply at 220kV Kemar since AR operation of nearby fault on VM2 Line earlier. all the three source feeders tripped. Meanwhile, firm was requested to submitt offer to implement the AR fucntion as per SRPC c. In addition there was complete loss of supply at 220kV recommendations for generating station. MSEZ, 220kV Kavoor and 220kV Puttur stations since these stations were radially fed from 220kV Kemar station. KPCL mail dated 26.11.2020 & 22.01.2021: The firm was requested to submitt offer to implement the AR fucntion as per SRPC recommendations for generating station
93/II/ 12 Tripping of 400 kV 26-09-2020 at 01:06 • 400 kVMahabubnagar (Veltoor) - Raichur tripped on spurious i. KPCL to submit a report regarding mal-operation of the contacts of PRD instrument of reactor KPCL KPCL mail dated 22.01.2021: Pending Mehaboobnagar - Raichur Hr operation of Y-phase PRD protection of line reactor and DT of 400 kV Mehaboobnagar – Raichur line. i) Suspected that moisture content in PRD terminal board caused the mal operation & suitable was sent to Veltoor end. ii. KPCL to configure DR/EL for operation of all protections. measures will be taken up to avoid repetition of this mal- operation. • As reported, PRD operated on spurious fault due to mal- ii) Configured - Completed operation of the contacts of PRD instrument.
94/I/12 Complete outage of 220kV 02-Dec-20 Zone-1 distance protection of 220kV Kadra - Kaiga line i. KPCL to revise ∆I settings in Micom protection relay being used on 220 kV Kadra – Kaiga at KPCL Yet to be informed Pending Kadra PH of KPCL 14:01 hrs operated at 220kV Kadra end and LBB operated since the line Kadra end. was under NFBC during antecedent condition. Due to ii.KPCL to examine the feasibility of providing an earth switch to line-CT on line side on all 220 operation of LBB protection, all the elements connected to Bus- kV lines at their 220 Kadra PH, and take steps to provide the same, if feasible 1 tripped at 220kV Kadra. Since all the elements were connected only to Bus-1 during antecedent condition, there was complete loss of supply. There was no generation at Kadra during this event
94/II/16 Tripping of 400 kV BTPS- 08-Nov-20 As per the report submitted, line tripped on operation of OVR, i. KPCL to evaluate transient performance of CVTs at BTPS GS and to verify OVR grading KPCL Yet to be informed Pending JSWEL Toranagallu 21:45 hrs St-1 protection operated at BTPS end and DT was received at implemented at 400kV BTPS GS. JSWEL end. As per the DR of BTPS end, voltages observed ii. KPCL to configure DR’s & EL’s of protection relays of all 400 kV lines at their BTPS station are: Vr-242kV, Vy-239kV and Vb-235kV. Since the voltages for capturing OVR protection operation (OVR-1_start and OVR-1_trip, OVR-2_trip). at BTPS end are within limits, operation of OV St-1 protection at BTPS end needs review.
94/II/28 Trippings at 400kV Jindal 29-Nov-20 Units 1,3,4 and 5 at Jindal TPS (780 MW) tripped due to flash i. KPCL to furnish a report regarding tripping of Generating Unit-2 on turbine protection trip at KPCL Yet to be informed Pending TPS of JSWEL and 400kV 13:16 hrs over in GIS Chamber and Units#1 and 2 at BTPS (906 MW) their BTPS station during Bus fault at JSWEL GS. BTPS of KPCL tripped due to electrical side problem. Complete Generation ii. KPCL to check & revise Reverse Zone (Z4) settings adopted on all 400 kV lines rmanating loss of 1690 MW. 400kV Jindal – BTPS line, 400kV Jindal – from their BTPS station. BPS line-1, and 400kV BTPS – Hiriyur line-1 also tripped iii. KPCL to provide appropriate time delay of say, 100 msec for ID fans tripping on detection of during this event. voltage dip.
Page 24 of 52 Annexure-C 40/I/1 GD-1 at 220kV Ambewadi 22-12-2014 Triggering incident was B-phase to earth fault in 1. Till the completion of R&M works for bus bar and LBB protection, KPTCL KPTCL Mail received on 28-04-2015: Pending Station of KPTCL at 21:22 hrs 220kV Ambewadi- Nagzari line-1. B-pole of breaker shall explore the possibility of having split bus operation at Ambewadi and 1. In view of operating 220kV Ambewadi SS in split bus mode, action is being did not open at Ambewadi end. LBB protection not submit the details of the same to PCSC forum. taken up by KPTCL. Problem in the 220kV bus coupler breaker is attended and available at Ambewadi end. All elements tripped on isolator overhauling work is under progress. Spilt bus operation at Ambewadi Zone-2 from remote ends. 2. KPTCL shall provide the details of the tripping of Supa hydro station will be made possible at the earliest. --- Pending connected downstream from 110 kV bus. 2. ICT Protection system at Ambewadi and trippings occured at Supa GS during the instance is checked up and remedial measures already furnished in this KPTCLregard. Mail dated 16.12.2017 & Review Meeting dated 19.12.2017: 1. Recommended works at Ambewadi have not been taken up due to various problems faced due to poor response from the turn key agency M/s ERL. A site meeting is planned during this month to discuss about further plan of action for attending SRPC recommendations pertaining to the Sub station.
The issue was discussed in the review meeting. Considering the importance of the substation and delay in executing the works, it was decided to escalate all pending issues relating to Ambewadi SS to KPTCL top Management for early completion.
KPTCL mail dated 20.12.2018: 1. The outstanding protection issues pertaining to Ambewadi were appraised to the management and proposal for construction of new GIS SUb stations has been approved by KPTCL management. In view of attending protection audit recommendations pertaining to Ambewadi SS without linking with new Station proposal, action has been taken to include the works in extended scope of R&U project awarded to M/s GE T&D India Limited. Addition materials required are yet to be supplied by M/s GE.
Review meeting on 27.06.2019: 1. KPTCL will inform the status on progress of work.
KPTCL mail dated 12.02.2020: 1. BBP provided at Ambewadi SS. - Completed
41/I/4 Complete outage at 220kV 27-01-2015 at R-Phase to ground fault occurred on 220kV Sedam- 1. KPTCL to provide Bus bar and LBB protections for 220 kV bus at Sedam KPTCL Mail received on 28-04-2015: Pending 1. Status? Sedam Substation of 8.00 hrs Shahpur line. Fault not cleared from Sedam end due S/s. Procurement of Bus bar and LBB protection is in the final tendering stage. 2. KPTCL (GD-1) to stuck-breaker condition. While the Sedam- Action is being taken to restore the carrier protection for 220kV Sedam-Tandoor Sahapur line tripped from Shahapur end in Zone-1, 2. KPTCL to implement A/R feature on 220 kV Sedam-Tandur inter-state line. AR will be enabled. the other 220 kv lines from Sedam tripped at remote line. Mail received on 29-07-2015: ends in Zone-2. This caused complete outage of 1. Procurement of Bus bar and LBB protection is in the final tendering stage. 220kV Sedam substation. 2. Action is being taken to restore the carrier protection for 220kV Sedam- Tandoor line. AR will be enabled after restoration of PLCC. KPTCL mail received on 23-01-2016: 1. Bus bar protection panels pocured and erected at Sedam. Wiring , testing ,commissioning is being taken up.Planned to complete by April 2016. 2. Action is being taken to restore the carrier protection for 220kV Sedam- Tandoor line. AR will be enabled after restoration of PLCC. KPTCL Mail recieved dated 22-11-2017: 1 & 2). Bus Bar Protection panel and required Wave traps are supplied under R&U. Wave trap to be commisioned in Tandoor line and PLCC to be restored.Once PLCC is restored AR will be enabled. The Wave traps required are supplied under R&U project and the same is to be commisioned at Sedam end for restoration of PLCC.
KPTCL Mail dated 16.12.2017: 1 & 2) Replacement of Bus Bar Protection is included under R&U project. Awarded to M/s GE Ltd. Panels have alredy been supplied by the Agency. The work will be taken up on top priority.
Review Meeting dated 19.12.2017: KPTCL informed that the works relating to put A/R in service are going on at their Sedam SS, and assured that it would be put into service by February, 2018.
KPTCL mail dated 20.12.2018: 1). Bus Bar Protection Work is under progress. Work will be completed in 2 months. ---- Pending 2). ---A/R was enabled from Sedam end on 03.11.2018 ----Completed.
Review meeting on 27.06.2019: 1. Timeline - September 2019 2. Completed
KPTCL mail dated 12.02.20220: 1. The work is under progress, expected to be put in to service before end of February 2020 2. AR was implemented. But due to problem with single phase trip relays the same was disabled. Now the same has been attended and expected to be put in to service before end of February 2020
Page 25 of 52 Annexure-C 42/I/1 Complete outage of 220kV 15-02-2015 Fault occurred in 220kV Sedam-Shahpur line 1. KPTCL to provide Bus Bar protection and LBB protection at Sedam S/s and KPTCL Mail received on 27-05-2015: Pending Sedam substation of at 14:24 hrs furnish the status of their implementation to PCSC forum. 1. Bus Bar protection will be provded under R&U. KPTCL 2. A/R yet to be enabled. 2. KPTCL to implement A/R feature on 220 kV Sedam-Tandur inter-state line. Mail received on 29-07-2015: 1. Procurement of Bus bar and LBB protection is in the final tendering stage. 2. Action is being taken to restore the carrier protection for 220kV Sedam- Tandoor line. AR will be enabled after restoration of PLCC. KPTCL Mail Recieved dated 22-11-2017: Bus Bar Protection panel and required Wave traps are supplied under R&U. Wave trap to be commisioned in Tandoor line and PLCC to be restored.Once PLCC is restored AR will be enabled. KPTCL Mail dated 16.12.2017: Review meeting on 27.06.2019: 1. Timeline - September 2019 2. Completed
KPTCL mail dated 12.02.20220: 1. The work is under progress, expected to be put in to service before end of February 2020 2. AR was implemented. But due to problem with single phase trip relays the same was disabled. Now the same has been attended and expected to be put in to service before end of February 2020
42/I/2 Complete outage of 220 kV 12-03-2015 at Fault in 220kV Ambewadi-Nagjheri line-2 1. KPTCL shall provide A/R feature on Ambewadi – Ponda 220 kV D/C inter- KPTCL Mail received on 29-07-2015: Pending (GD) Ambewadi substation of 7:51 hrs state line. 1. Procurement of Bus bar and LBB protection is in the final tendering stage. KPTCL 2. Action is being taken to restore the carrier protection for 220kV Sedam- 2. Till the completion of R&M works for bus bar and LBB protection, KPTCL Tandoor line. AR will be enabled after restoration of PLCC. shall explore the possibility of having split bus operation at Ambewadi and submit the details of the same to PCSC forum. KPTCL Mail Recieved dated 22-11-2017 & 16.12.2017: 1.Enabling the AR feature was discussed during PCSC meetings and since Ambewadi-Ponda and Ambewadi-Xeldom lines are radial lines, it was decided that enabling AR is not required. To clear the faults in the abovelines early, the KPTCL mail dated 20.12.2018: The protection issues pertaining to Ambewadi was appraised to the management and proposal for construction of new GIS SUb stations has been approved by KPTCL management. Further as per SRPC directions and in view of attending protection audit recommendations pertaining to Ambewadi SS without linking with new Station proposal, action has been taken to include the works in extended scope of R&U project awarded to M/s GE T&D India Limited. Addition materials required are yet to be supplied by M/s GE. work expecnted to be completed in 5 months.
Review meeting on 27.06.2019: 1. Since 220kV Ambewadi -Ponda line is radial, this recommendation is dropped. 2. Timeline will be in timated by KPTCL
KPTCL mail dated 12.02.2020: 1. 220kV line breaker replacement work under progress at Ambewadi. AR will implemented after replacement of CBs -- Pending 2. BBP provided at Ambewadi -- Completed
Page 26 of 52 Annexure-C 48/I/3 Outage of 220kV 30-09-2015 at 220kV Ambewadi-Nagjheri line-2 tripped on B- KPTCL to fast-track providing A/R on all 220 kV lines emanating from KPTCL KPTCL mail received on 23-01-2016: Pending Status? Ambewadi station in 10:41 hrs phase to earth fault. This resulted in loss of supply Ambewadi SS to prevent Station shut-down on temporary faults. Will be complied in a months time. Karnataka to 220kV Ambewadi bus. 220kV Ambewadi-Ponda KPTCL Mail Recieved dated 22-11-2017: line-1&2 were hand tripped after deenergization of Enabling the AR feature was discussed during PCSC meetings and since bus at Ambewadi. Ambewadi-Ponda and Ambewadi-Xeldom lines are radial lines, it was decided that enabling AR is not required. To clear the faults in the abovelines early, the timings of the Zone 2 was reduced to 150mS and the Back Up EFR timings have been reducedto 150mS. KPTCL Mail dated 16.12.2017: Enabling the AR feature was discussed during PCSC meetings and since Ambewadi-Ponda and Ambewadi-Xeldom lines are radial lines, it was decided that enabling AR is not required. To clear the faults in the abovelines early, the timings of the Zone 2 was reduced to 150mS and the Back Up EFR timings have been reduced to 150mS. In view of the above, it is requested to drop the issue KPTCL mail dated 20.12.2018: The protection issues pertaining to Ambewadi was appraised to the management and proposal for construction of new GIS SUb stations has been
Page 27 of 52 Annexure-C 52/I/3 Complete outage of 220 kV 22-02-2016 at 220kV Bus Bar protection operated during failure of KPTCL to operate 220 kV Shimoga on multi-bus operation under normal KPTCL KPTCL Mail received dated 25-04-2017: Pending Shimoga substation 15:03 hrs R phase CT in DVG-2 line bay. conditions, and put it on single-bus operation only under emergency conditions. Replacement of existing BBP by new BBP with 4 zone protection is being taken up under R&U. KPTCL Mail Recieved dated 22-11-2017: GE Ltd has already supplied the necessary Bus Bar protection panels for replacement of the existing static type BBP by new numerical BBP with 4 zone protection under R&U project. The work of commissioning the same will be taken up shortly.
KPTCL Mail dated 16.12.2017: Due to operational constraints two/ multi bus operation is not being implemented.
Review Meeting dated 19.12.2017: It was noted that Shimoga SS is having required configuration for providing double-bus operation. However, due to large no. of feeders (15 in no) with KPTCLvariable gnerationmail dated at certain20.12.2018: remote ends like Varahi, the flows on these lines are Bus sectionaliser breakers have to be provided for operating Shimoga in multi bus mode. Estimates have to be prepared by CEE,TZ,Hassan. Work expected to be completed in 1 year.
KPTCL mail dated 12.02.2020: After commissioning of numerical BBP bus split trial operation was made. However for providing more reliability, action is being taken for providing bussectionaliser breakers.
62/II/5 Tripping of 220 kV South 20-01-2017 at Triggering incident was fault in 66 kV Somanahalli - KPTCL to provide numerical Busbar Protection at their 220 kV Somanahalli SS KPTCL KPTCL mail received dated 25.04.2017: Pending Bus and connected 14:34 hrs Bannerghatta line and fault was cleared by operation at the earliest. Numerical BBP is being provided under R&M works elements (220kV HSR, of Back-up OCR at Somanahalli end. 220kV Nagnathpura, 220 KPTCL Mail Recieved dated 22-11-2017: kV Harohalli, 220 kV Tesing & Commissioning of numerical BBP at Somanahalli is under progress. Subramanyapura, 220 kV There was some technical issue wth BBP scheme supplied to Somanahally which Tataguni, 220 kV Mallur is being finalised in consultation with OEM SIFANG. Numerical BBP will be and 400/220kV ICT-2 and commissioned at Somanahally within a month's time. 3) at 400/220kV KPTCL Mail dated 16.12.2017: Somanhalli substation of Numerical Bus Bar protection Scheme will be commissioned at Somanahally KPTCL before end of December 2017. (Load loss: 850 MW) KPTCL mail dated 20.12.2018: The work of providing Bus Bar Protection to 220kV buses is incuded under R&M works envisaged at Somanahally. The R&M work is expected to be completed before end of March 2019 ----- Pending
Review meeting on 27.06.2019: status of work and timeline will be given by KPTCL
KPTCL mail dated 12.02.2020: The work is to be executed by the R&M turn key agency
74/I/2 Complete outage of 220 kV 02-04-2018 at Loss of supply occurred to 220 kV Ambewadi 1). KPTCL to review operation of SPS at NPH for proper functionality and KPTCL KPTCL mail dated 20.12.2018: Pending Ambewadi station 13:46hrs station due to tripping of 220kV Nagzhari- changed network conditions (reduction of generation with tripping of evacuating 1). To be reviewed. Expected to be completed in 1 month.---- Pending Ambewadi line-2 (Source) from Nagzhari power lines) and put it into service at the earliest. station. After bus dead, Ambewadi-Ponda lines – 1 2), Being followed ----- Pending & 2 were hand-tripped. In antecedent conditions, 2). KPTCL to furnish equipment failure report of the current incident (R-phase 220kV Ambewadi - Nagjheri ckt-1, 220kV CT in Nagjheri – 1 bay at Ambewadi SS) to PSE&TD Division of CEA with a Review meeting on 27.06.2019: Ambewadi-Narendra Ckt-1 &2 were out of service. copy marked to SRPC. 1. Nagjheri SPS shall be studied in view of changed system configuration 2. Completed
KPTCL mail dated 12.02.2020: The logic is being reviewed by SRLDC by conducting system studies for the changed network configuration
74/II15 Multiple Trippings at 21-04-2018 at Triggering incident was fault in 220 kV Davanagare KPTCL to put double-bus operation at their 220 kV Guttur substations by KPTCL KPTCL mail dated 20.12.2018: Pending 400/220kV Guttur station 12:50 hrs - Shimoga line. Bus bar protection operated at attending to Bus-2 CVT problem. Bus-2 CVT problem is attended. However due to breaker replacement works, Guttur resulting in tripping of all the connected 220kV side operated in single bus mode. elements. 220 kV Guttur was on single bus operation due to CVT problem in Bus-2. Review Meeting dated 20.12.2018: KPTCL informed that double-bus operation at their 220 kV Guttur would be provided within two months.
Review meeting on 27.06.2019: Timeline will be communicated by KPTCL
79/III/9 Tripping of 400 kV JSWEL 29-09-2018 R-phase to earth fault occurred in line. Auto-reclose KPTCL to furnish a detailed report on tripping event bringing out reasons for KPTCL Review Meeting on 21.12.2018: Pending –Guttur line at 11:30 hrs was not attempted at JSWEL due to DT receive. At DT sending from Guttur end to JSWEL on 400 kV Guttur - JSWEL line along KPTCL was aksed to furnish status of implementation of the recommendation Guttur end auto-reclose could not be validated with with remedial action taken to PCSC forum. given at the earliest. DR/EL. Review meeting on 27.06.2019: report will be submitted by KPTCL
Page 28 of 52 Annexure-C 80/II/7 Tripping of 400 kV JSWEL- 17-10-2018 at Triggering incident was R-phase to earth fault in KPTCL to examine the reasons for sending of DT from Guttur end to JSWEL KPTCL Review meeting on 27.06.2019: Pending Guttur line 02:04 Hrs line. At Guttur end there was operation of pole end, and furnish an action taken report including remedial measures taken to report will be submitted by KPTCL discrepancy and resulted on tripping of Y & B pole rectify the same. after a duration of 2 seconds from the occurrence of fault. FIR, DR & EL of Guttur end were not furnished. 82/I/4 Complete Outage of 220kV 06-02-2019 at Fault occurred while test charging of 220kV KPTCL to investigate the reason for non-tripping of 220kV Ambewadi - KPTCL Review meeting on 27.06.2019: Pending Ambewadi Station of 14:51hrs Ambewadi – Nagjheri Line -2 from Ambewadi end. Nagjheri line-2 on operation of SOTF and submit a report regarding the same to report will be submitted by KPTCL KPTCL Suspected stuck breaker condition at Ambewadi SRPC. Also KPTCL to take necessary measures in order to ensure healthiness of end) led to clearing of fault by tripping of remote breaker before testcharging of any line. end breaker in Zone-2. LBB protection is not active at 220kV Ambewadi station.
82/II/12 Tripping of 400kV Kaiga- 07-02-2019 Line-1 tripped due to insulator flashover. Line-2 KPTCL is recommended to take necessary measures to ensure that Main-I and KPTCL Review meeting on 27.06.2019: Pending Guttur line-1&2 at 11:49 hrs tripped due to zone-3 operation at Kaiga and Direct Main-II at Guttur end shall be of different types (make and model) coherent with KPTCL informed that the recommendation has been included as part of R & M trip receive at Guttur the general protection philosophy followed in SR region. work. Timeline will be informed
84/II/12 Tripping of 400kV DHONI 18-04-2019 at Triggering incident was failure of B-ph CB of 1. KPTCL to send equipment failure report, corresponding to the failed CB at KPTCL Yet to be informed Pending GUTTUR line- 1 18:59 hr. 400kV Dhoni-Guttur line at Dhoni end. This Dhoni SS, to CEA. resulted in the operation of LBB of bus-1 and DT 2. KPTCL to ensure time synchronization at Guttur end. was sent to Guttur end
84/II/16 Tripping of 400 kV 01-05-2019 at 02:29Line hr. tripped on operation of over voltage stg-2 at KPTCL to ensure time synchronization of DR and EL with GPS signal at KPTCL Yet to be informed Pending Nelamangala-Mysore line-2 Nelamangala end Nelamangala end.
84/II/24 Tripping of 400/220 kV 13-05-2019 at ICT-3 tripped on operation of 59N neutral KPTCL to inform PCSC forum regarding the changes implemented in Hoody KPTCL Yet to be informed Pending ICT-1&3 at Hoody 15:35 hr. displacement relay. ICT-1 tripped on OCR. ICT SPS and to ensure time synchronization of relays at Hoody SS. Substation
85/I/4 Tripping of 220kV Sedam-RTPS 14-06-2019 Tripped on Directional Earth Fault indications in 1. KPTCL is recommended to enable A/R on all lines emanating from 220kV KPTCL KPTCL mail dated 12.02.20220: Pending line-1&2 and 220kV Sedam- at 02:00 hrs Main-2 relay at Tandur end for fault at Raichur end. Sedam SS. The work is under progress, expected to be put in to service before end of Tandur line Sedam end details not furnished. 2.KPTCL is recommended to commission BBP at 220kV Sedam SS February 2020 immediately.
85/II/5 Tripping of 400/220 kV ICT-3 at 19-05-2019 As per FIR, ICT-3 got tripped on operation of High 1. KPTCL is recommended to enable auto-reclosure on all lines emanating KPTCL Yet to be informed Pending Nelamangala substation at 16:11 hrs Set Over current trip on 400kV side from 400/ 220kv Neelamangala SS and to ensure time synchronization of relays at Neelamangala SS.
85/II/11 Tripping of 400kV Hoody- 25-05-2019 Line tripped at Hoody end only and was holding KPTCL is recommended to check the spurious operation of SOTF protection at KPTCL Yet to be informed Pending Yelahanka line-1 at 20:41 hrs from Yelahanka. Hoody SS and submit a report to SRPC regarding the same .
85/II/12 Tripping of 400/220 kV ICT-1at 26-05-2019 LV side of 400kV/220kV 315MVA ICT#1 Guttur 1. KPTCL is recommended to submit a report to SRPC after the CB pressure KPTCL Yet to be informed Pending Guttur Substation at 10:00 hrs got tripped due to CB lockout (B phase)because of leakage problem is attended by OEM. low SF6 gas in the CB 2.. KPTCL to ensure that during recharging of Circuit breakers, cylinders with Non-return valve only are used to prevent sudden pressure drop in Circuit breakers.
85/II/22 Tripping of 400kV Dhoni- 06-06-2019 Line got tripped at Dhoni end. From DR Zone-3 KPTCL is recommended to submit a report regarding PSB maloperation along- KPTCL Yet to be informed Pending Munirabad line at 02:01 hrs start, PSB and A/r block was observed. with the RM suggested by OEM. Proper legends shall be ensured for digital signals at Doni end.
85/II/27 Tripping of 400/220kV ICT-2 at 16-06-2019 ICT-2 got tripped on operation of over-flux KPTCL is recommended to adopt v/f settings as per manufacture suggested KPTCL Yet to be informed Pending Hoody substation at 19:20 hrs protection curve. v/f setting for alarm: 1.1 time Vnominal; Time delay 10 seconds; v/f trip setting : v/f is 1.2 time Vnominal;Time delay 60 seconds
Page 29 of 52 Annexure-C 85/II/29 Tripping of 400kV Hiriyur- 22-06-2019 at 400kV Hiryur-Nelamangala line-1 : 'Y' phase KPTCL is recommended to submit equipment failure report to CEA regarding KPTCL Yet to be informed Pending Nelamangala line-1 and 400kV 04:06hrs bushing of Hiriyur line-1 reactor failed at the reactor bushing failure and also to sort out time synchronization issues of Gooty-Nelamangala line Nelamangala end resuting in a R-Y phase fault. 400kV Hiriyur-Nelamangala line. Direct trip was sent to Hiryur.
400kV Gooty-Nelamangalaline : Line tripped at Nelamangala end only due to mal-operation of Main- 2 distance protection relay (THR).
85/II/30 Tripping of 400/220kV ICT-1&2 24-06-2019 400/220kV ICT-1&2 at Munirabad end got tripped KPTCL is recommended to submit equipment failure report to CEA regarding KPTCL Yet to be informed Pending at Munirabad substation at 20:50 hrs due to operation of High set of backup earth fault the CT and PT failure. relay during failure of Y phase CT in 220kV Munirabad-Kalyani steel feeder at Kalyani steel end
86/II/9 Tripping of 400 kV Neelamangala- 15-07-2019 line tripped on operation of OV st-1 protection at KPTCL to configure both OVR start and OVR trip in DR or EL at 400 kV Neelamangala SS. Time KPTCL KPTCL mail dated 30.10.2019: Pending Mysore line-2 at 2:02 hr Neelamangala end and DT was received at Mysore end. DR of sync issues at 400 kV Neelamangala SS shall also be sorted out immediately. DR triggering has been done for OVR stage-1 operation in Mysore-2 line . GPS time Nelamangala end was not available for validation of OV synchronisation of Power Grid bays will be taken up along with panel replacement work protection operation envisaged under R&M. OVR_start also to be configured.
Page 30 of 52 Annexure-C 49/I/3 Complete outage of 220kV 29.10.2015 at 220kV Nagjheri-Ambewadi line-1 tripped at 13:33 1. KPCL to provide A/R on all 220 kV lines emanating from Nagjheri PH. KPCL/ KPTCL KPTCL Mail Recieved dated 22-11-2017: Pending Ambewadi Substation of 14:34 hrs hrs due to B phase to earth fault. Ambewadi was 1. coordination of KPCL has been requested for enabling AR lines terminated to KPTCL radially fed from Nagjheri power station through 2. KPTCL to provide A/R on all 220 kV lines emanating from Ambewadi SS. Nagajari. 220kV Nagjheri-Ambewadi line-2. Tripping of this 2. AR will be enabled at Ambewadi end for lines other than Ponda and Xeldom line caused 220kV Bus shut down at Ambewadi and lines during retrofitting of Back Up protection by Distance protection relay at remaining lines and transformers were hand tripped Ambewadi.
KPTCL Mail dadted 16.12.2017 & Review Meeting dated 19.12.2017: 1. KPTCL informed that Coordination of KPCL has been requested for enabling AR lines terminated to Nagajari. --- Pending 2. KPTCL informed that AR would be enabled at Ambewadi end for lines other than Ponda and Xeldom lines during retrofitting of Back Up protection by Distance protection relay at Ambewadi. -- Pending
KPTCL mail dated 20.12.2018: 2). Readiness from KPTCL for implementing AR is already confirmed to KPCL. Decision pending from KPCL end. KPCL mail dated 23.03.2019: 1) Proposal will be taken up for replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850. Prepration of specification is under progress.
KPCL mail dated 13.05.2019: 1) Budgetary offer obtained for replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850. Preparation of estimation and specification is under progress.
KPCL mail dated 25.05.2019 & 16.07.2019: 1) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. Approval of NLDC for DPR is awaited. Further, availing administrative approval for issue of NIT for replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 and preparation of estimation and specification is under progress. Timeline for completion of work is July 2020.
KPCL mail dated 30.10.2019 1) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. Approval of NLDC for DPR is awaited. NIT issued through e-portal on 16.09.2019. Pre- bid meeting was held on 10.10.2019. Finalising of replies to pre-bid queries is in KPCL mail dated 17.12.0219 and 11.02.2020: 1) ) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. Approval of NLDC for DPR is awaited. NIT issued through e-portal on 16.09.2019. Cover- 1 opened on 02.12.2019. Technical evaluation is in progress.
KPCL mail dated 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: 1) Replacement of existing PZ1000 relays with new version Numerical Line protection relays having IEC61850 is included in PSDF Phase-II DPR. NIT issued through e-portal on 16.09.2019. Tender evaluation is completed. Approval of NLDC for DPR is awaited for placing PO on L1 agency
51/I/3 Complete outage of 220 kV 22-02-2016 at 220kV lines from Nagjheri power house started 1. To avoid tripping of transmission lines on transient faults, KPCL/ KPTCL is KPCL/ KPTCL Status informed during Special Meeting held on 03.06.2016: Pending Nagjheri power station and 12:36 hrs tripping from 11:00 hrs due to fault in lines. The recommended to carry out periodic patrolling of lines, and ensure their proper 1. KPTCL informed that the matter had been taken up with concerned Line 220 kV Ambewadi sequence of tripping is shown in SOE list. At 12:33 maintenance by carrying out jungle/ bushing clearance and trimming of tree Operation and Maintenance wing to carry out corridor clearance and maintenance substation of KPTCL hrs, 220kV Narendra-Ambewadi lines-1&2 got branches within the RoW of transmission lines as per the SRPC transmission as per schedule to avoid frequent line faults in this corridor. A letter had also tripped which resulted in loss of evacuation path to line patrolling guidelines (available under the menu item "All Uploads/ been addressed to Chief Engineer, Bhagalkot zone, to ensure lines in & around Nagjheri station resulting in tripping of running Operation/ Miscellaneous/ Transmission Line Patrolling Protocol / Guidelines Kali complex are maintained in healthy condition. --- Completed Units and complete outage at Nagjhheri power for Southern Region" on SRPC website). 2. KPTCL assurd that the final modified SPS would be implemented at Nagjheri station. 220kV Ambewadi station also got de- PH at the earliest. ------Pending energized due to tripping of source feeders i.e. 2. KPCL/ KPTCL to review operation of SPS at NPH for functionality 3. KPCL informed that Nagjhari- Kodasalli Lines 1 & 2 had been kept in service 220kV Narendra-Ambewadi-1&2 and 220kV (reduction of generation with tripping of evacuating lines) and healthiness. since 23.05.2016 @ 08.06hrs. Nagjheri-Ambewadi-1&2. --- Completed 3. KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into service if more than 200 MW generation from Kali Complex (with Nagheri Contribution not less KPTCL Mail received dated 28-06-2016: than 50 MW) is ensured on sustained basis. 2. Modifications to be carried in Nagzari SPS logic is submitted to SRLDC/SRPC for verification and approval Status received vide KPCL mail dated 14.06.2017: 1. Will be reviewed in consultation with EE(RT), KPTCL, Hubli. 3. Both the lines are in charged condition.
KPTCL Mail Recieved dated 22-11-2017: 1) & 3) --- Completed 2). Proposed revision in existing SPS scheme is already submitted to SRLDC/SRPC., Yet to be discussed and approved by the SRPC forum. --- KPTCL Mail dated 16.12.2017: 1) & 3). --- Completed. 2). Proposed revision in existing SPS scheme is already submitted to SRLDC/SRPC., yet to be discussed and approved by the SRPC forum --- Pending
Page 31 of 52 51/I/3 Complete outage of 220 kV 22-02-2016 at 220kV lines from Nagjheri power house started 1. To avoid tripping of transmission lines on transient faults, KPCL/ KPTCL is KPCL/ KPTCL Pending Nagjheri power station and 12:36 hrs tripping from 11:00 hrs due to fault in lines. The recommended to carry out periodic patrolling of lines, and ensure their proper 220 kV Ambewadi sequence of tripping is shown in SOE list. At 12:33 maintenance by carrying out jungle/ bushing clearance and trimming of tree substation of KPTCL hrs, 220kV Narendra-Ambewadi lines-1&2 got branches within the RoW of transmission lines as per the SRPC transmission tripped which resulted in loss of evacuation path to line patrolling guidelines (available under the menu item "All Uploads/ Nagjheri station resulting in tripping of running Operation/ Miscellaneous/ Transmission Line Patrolling Protocol / Guidelines Units and complete outage at Nagjhheri power for Southern Region" on SRPC website). station. 220kV Ambewadi station also got de- energized due to tripping of source feeders i.e. 2. KPCL/ KPTCL to review operation of SPS at NPH for functionality 220kV Narendra-Ambewadi-1&2 and 220kV (reduction of generation with tripping of evacuating lines) and healthiness. Nagjheri-Ambewadi-1&2. 3. KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into service if more than 200 MW generation from Kali Complex (with Nagheri Contribution not less than 50 MW) is ensured on sustained basis.
Annexure-C KPCL mail dated 16.07.2019: 1 & 3) Completed. 2) Letter addressed to KPTCL RT dated: 25.03.2019 for review and implementation of SPS at NPH. Reply from KPTCL is awaited.
KPCL mail dated 30.10.2019 and 17.12.2019 and 11.02.2020: 1 & 3) Completed. 2) KPTCL informed that Naghjeri SPS need to be revisited in view of changes in system configuration. Reply from KPTCL is awaited
KPTCL mail dated 12.02.2020: 1 & 3) Completed. 2. The logic is being reviewed by SRLDC by conducting system studies for the changed network configuration
KPCL mail dated 21.05.2020 & 27.07.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: 1 & 3) Completed. 2) KPTCL informed that Naghjeri SPS need to be revisited in view of changes in system configuration. Reply from KPTCL is awaited
Page 32 of 52 Annexure-C 53/I/3 Complete outage of 220kV 18-03-2016 at Ambewadi Narendra line-2 tripped on fault and 1. KPCL to furnish a report on the reasons for Unit-6 tripping at Nagjheri PH. KPCL/ KPTCL KPTCL Mail received dated 28-06-2016: Pending Ambewadi station of 14:40 hrs 220kV ambewadi Narendra line-1 tripped due to Modifications to be carried in Nagzari SPS logic is submitted to SRLDC/SRPC KPTCL and 220kV over-loading. Running Units at Nagjheri also tripped 2. KPCL/ KPTCL to modify suitably the SPS at Nagjheri Power House such that for verification and approval Nagjheri of KPCL during the event due to tripping of evacuating lines it would also factor in the over loading of Ambewadi-Narendra lines. Status received vide KPCL mail dated 14.06.2017: 3. KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into service if more than 1. Tripped since there was evacuation problem and there were only two lines NA- 200 MW generation from Kali Complex (with Nagheri Contribution not less 1 and NA-2 ---- Completed than 50 MW) is ensured on sustained basis. 2. Will be reviewed in consultation with EE(RT), KPTCL, Hubli. --- Pending 3. Both the lines are in charged condition. --- Completed.
KPTCL Mail Recieved dated 22-11-2017: 2. Proposed revision in existing SPS scheme is already submitted to SRLDC/SRPC., yet to be discussed and approved by the SRPC forum. --- Pending
KPTCL Mail dated 16.12.2017: 1) & 3). --- Completed. 2). Proposed revision in existing SPS scheme is already submitted to SRLDC/SRPC., yet to be discussed and approved by the SRPC forum --- Pending
Review Meeting dated 19.12.2017: 2. The SPS proposed by KPTCL was discussed and the PCSC forum suggested certain changes for suitable incorporation. KPTCL agreed to look into the same and assured that the modified SPS would be furnished by January, 2018.
Review Meeting on 21.12.2018: KPTCL informed that Nagjheri SPS shall be finalised in 1 month.
KPCL mail dated 23.01.2019 & 23.03.2019: 1) …Completed. 2) It shall be reviewd and Implemented by KPCL in coordination with KPTCL. 3) …Completed.
KPCL mail dated 10.05.2019 & 25.06.2019: 1. & 3. Completed 2) Letter addressed to KPTCL RT dated: 25.03.2019 for review and implementation of SPS at NPH. Reply is awaited.
Review meeting on 27.06.2019: 2. KPTCL informed that Naghjeri SPS need to be revisited in view of changes in system configuration.
KPCL mail dated 16.07.2019 & 30.10.2019 & 17.12.2019 & 11.02.2020 & 21.05.2020 & 27.07.2020 & 22.01.2021: 1 & 3) Completed. 2) Letter addressed to KPTCL RT dated: 25.03.2019 for review and implementation of SPS at NPH. Reply from KPTCL is awaited.
KPTCL mail dated 12.02.2020: 1. & 3. Completed 2. The logic is being reviewed by SRLDC by conducting system studies for the changed network configuration
KPCL mail dated 21.05.2020 & 28.09.2020 & 26.11.2020 & 22.01.2021: 1 & 3) Completed. 2) Letter addressed to KPTCL RT dated: 25.03.2019 for review and implementation of SPS at NPH. Reply from KPTCL is awaited.
87/II/25 Tripping of 400 kV 28-09-2019 at 1:38 Line tripped on operation of over voltage stg-2 protection at KPTCL to ensure relay pickup to drop off ratio of 0.98 and above for relays configured for KPTCL Yet to be informed Pending Nelamanagala-Mysore line-2 hr. Nelamangala and direct trip received at Mysore overvoltage protection.
88/II/13 Tripping of 400kV Talaguppa 19-10-2019 at 16:22 Line tripped on operation of OV St-1 protection at KPTCL to configure OVR_start in DR or EL and to sort out time synchronization issues between KPTCL Yet to be informed Pending –Nelamangala line Hr. Nelamangala end and DT was sent to Talaguppa end. Talaguppa and Nelamanagala ends.
88/II/14 Tripping of 400/220kV ICT-2 at 22-10-2019 at 02:12 ICT#2 at Guttur got tripped on operation of Buchholz KPTCL to provide shielding for Buchholz relay to prevent such mal-operations. KPTCL Yet to be informed Pending Guttur Hr. protection due to suspected moisture entry during rain.
Page 33 of 52 Annexure-C 89/I/1 Complete loss of supply at 220 14-12-2019 at 10:56 • Triggering incident was fault in 220 kV Hubli-Narendra Line- i. KPTCL to ensure A/R is in service in all 220 kV lines emanating from 220kV Hubli SS and KPTCL KPTCL vide mail dated 22.05.2020 informed that Pending kV Hubli SS, 220 kV Bidnal SS Hr. 2. 220kV Bidnal SS. Recommendations made by SRPC on this incident are communicated to various wings. Action of KPTCL and 220 kV Nagjheri • Due to cascaded tripping of connected lines and loss of ii. KPTCL was requested to ensure proper planning of outages of transmission lines (i.e., outage taken details/latest status is yet to be received. The same will be complied to SRPC upon receipt of GS of KPCL evacuation, there was complete loss of supply at: planning should be as per N-1 contingency planning and not to cause stress on the system to confirmation from different wings 220 kV Hubli SS & avoid complete outages due to fault in the Nagjhari- Hubli corridor. 220 kV Bidnal SS of KPTCL and iii. KPTCL to explore the possibility of split bus operation at 220 kV Hubli SS, in the event of 220 kV Nagjheri GS of KPCL outage of any of the 220 kV Hubli – Narendra line, to prevent overloading of other line (Narendra line) and 220kV Bidnal – Narendra line. iv. KPTCL to submit the SPS for shedding of loads planned at 220kv Hubli SS. v. KPTCL to expedite finalization of SPS at 220kV Nagjheri SS considering LILO of one circuit of 220kV Haveri-Narendra line at Bidnal as part of RE evacuation and submit the study to SRPC and SRLDC for scrutiny/ finalisation. vi. KPTCL to ensure time synchronization of relays at 220kV Hubli, 220kV Bidnal, 220kV Soundatti and 220kV Harthi. vii. KPTCL to explore the possibility of conductor strengthening in Nagjheri – Hubli- Bidnal and surrounding areas.
89/1/2 Complete loss of supply at 220 25-12-2019 at 17:44 Triggering incident was line to line fault in 220 kV Shimoga- i. KPTCL to ensure Double Bus operation at 220 kV Shimoga SS to ensure reliability to prevent KPTCL Pending kV Shimoga SS of KPTCL. Hr. Sharavathi line -4. complete outage of Substation. Bus-1 Bus bar protection operated at 220 kV Shimoga ii. KPTCL, in coordination with KPCL, to enable A/R in 220 kV Shimoga – Sharavathy lines. resulting in complete loss of supply since all the elements were connected to Bus-1 during antecedent conditions.
89/III/1 Tripping of 400kV Kaiga – 11-10-2019 at 08:49 • Triggering incident was Y phase to Earth fault in the line. • KPTCL to study the A/R block signal issued due to misinterpretation of single phase fault as KPTCL KPTCL vide mail dated 22.05.2020 informed that SEE, RT Circle,Chitradurgain coordination Pending Guttur Line-2 Hr. • At Kaiga end, fault was detected in zone-1, A/r operated multi phase fault by distance relay (P442) and take suitable remedial actions. with EEE,Guttur to arrange for checking the healthiness of AR scheme for Guttur-Kaiga lines And successfully. 26-10-2019 at 12:42 • At Guttur end, fault was sensed in zone-1 and A/r not Hr. operated. • Non operation of A/r at Guttur end needs review.
90/I/8 Complete outage of 220kV 19-03-2020 at 17:08 During antecedent conditions, all the elements were connected KPTCL to take necessary measures to prevent mal operation of BBP at Shimoga during single-ph KPTCL Yet to be informed Pending Shimoga station of KPTCL Hr. to Bus-1 North bus at 220kV Shimoga SS. Triggering incident to line fault and ensure double bus operation at 220kV Shimoga SS. was R –N fault in 220kV Shimoga - Varahi line-2 due to insulator decapping. At the same time, 220kV Bus-1 BBP maloperated at 220kV Shimoga SS. All the elements were connected to Bus-1, which resulted in the complete loss of supply at 220kV Shimoga SS.
91/I/7 Complete outage of 220kV 9-05-2020 at • Triggering incident was snapping of earth conductor at second KPTCL to share the details of BBP commissioning schedule. KPTCL Yet to be informed Pending Peenya SS of KPTCL 06:29Hrs tower from 400 kV receiving station Nelamangala. • All other connected lines at 220kV Peenya tripped resulting in complete outage of 220kV Peenya station
91/I/9 Multiple Tripping in 18-05-2020 at • At 10:10hrs, 220kV Tumkur -_PGA’halli line was taken KPTCL is recommended to check the distance zone settings at 220kV KIADB SS since, it picked KPTCL Yet to be informed Pending 400kV/220kV Tumkur SS and 10:14Hrs under shutdown for AMP works. up in Zone-1 for a fault in remote station. Complete outage of 220kV • At 10:14hrs, bus fault occurred at 220kV Tumkur_PG SS due Anthrasanahalli SS of KPTCL to inadvertent closure of Bus-1 Earth Switch of A’halli line-2 while Bus-2 isolator of A’halli line-2 was in closed condition. • Due to non-operation of BBP at 220kV Tumkur_PG SS, fault was cleared by tripping of remote end feeders on Zone-2 operation and 400kV/220kV Tumkur ICT-1, 2 and 3 got tripped on operation of HV side directional OC protection. • This resulted in de-energization of 220kV Tumkur_PG bus. • Since 220kV A’halli SS was radially fed from 220kV Tumkur_PG SS, this resulted in complete loss of supply at 220kV A’halli SS of KPTCL .
91/I/10 Complete loss of supply at 220kV 24-05-2020 at • 220kV Manyata - Yelanhanka line tripped on Zone-1, distance KPTCL to explore the possibility of providing double bus at 220kV Hebbal SS. KPTCL Yet to be informed Pending Manyata and 220kV Hebbal SS 14:55Hrs protection due to R-Y fault. of KPTCL • As reported at tower location 67, tarpaulin sheet fell on the line. • Since the only incoming source to 220kV Hebbal was from Manyata, tripping of 220kV Manyata - Yalahanka line resulted in complete loss of supply at 220kV Manyata and 220kV Hebbal stations of KPTCL.
94/I/3 Complete outage of 220kV 17-Oct-20 Triggering incident was failure of i. M/s. Gamesa Ltd./KPTCL to restore Double bus operation at 220kV Nandihal SS after KPTCL Yet to be informed Nandihal SS, Bijapur SS, and 22:35 hrs Y-ph Metering CT connected to Nandihal - GM Navara line-1. replacing failed bus coupler CT. Indi SS Bus bar protection operated at 220kV Nandihal station and all Ii. M/s. Gamesa Ltd./KPTCL to submit Equipment failure report for failed CT to CEA with a connected elements tripped. There was supply failure at 220kV copy to SRPC Indi and Bijapur stations, since these station are radially fed from 220kV Nandihal station.
94/I/5 Complete outage of 220kV 31-Oct-20 Triggering incident was CT Blast in Bus-coupler bay at 220 kV KPTCL to expedite restoration of double bus operation, and ensure time synchronisation of KPTCL Yet to be informed Narendra Substation of KPTCL 23:47 hrs Narendra SS. All connected elements at 220 kV Narendra relays at their 220/ 110 kV Narendra SS. station tripped on Bus bar protection resulting in complete outage of the station
Page 34 of 52 Annexure-C
Tamil Nadu
62/II/7 Tripping of running Units 25-01-2017 at Failure of Bus Section-I Y-ph CT resulted in 1. TANGEDCO to replace existing Check-Zone relay with a new one possessing TANGEDCO TANGEDCO mail dated 15.04.2017: Pending Status? & 230kV feeders at 22:36 hrs operation of bus-bar protection for Bus Sections -I & required performance. 1) New Relay is tested and ready for replacement.Now all 5 units are in Tuticorin TPS of II. Running Units#1, 4 and 5, 230 kV Kayathar, service.The relay will be replaced when lesser units are in service. --- Pending TANGEDCO 230kV Kudankulam, 230kV Sterlite, Station 2. TANGEDCO to take steps to provide numerical busbar protection at their 220 2.a)Steps are taken to renovate & mordernization of all the control panel into Transformer-1, 2 & 3 got tripped during the kV Tuticorin TPS. TANGEDCO may also explore providing dual CT’s (on Numerical based control panels. --- Pending (Gen Loss: 640 MW) incident. Unit – 2 & 3 were not in service. either side) for all B/S breaakers at the time of commissioning of numerical 2.b) Since 230 KV indoor switchyard has no spare space providing dual CT`s is BBP, if there were no space constraints. not fessible. -- Completed 3) Procurement of EL & DR is under progress. --- Pending 3. TANGEDCO to take steps to provide for standalone Event Logger (EL) and standalone Disturbance Recorder (DR) with automatic downloading facility to a TANGEDCO mail dated 26.04.2017: centralized server. 1) Check zone New Relay is replaced on 17.04.2017 -- Completed. 2. --- Pending 3. --- Pending
TANGEDCO mail dated 13.12.2017: 2).P & C wing gives clearance to TTPS to procure the Bus bar protection relays and protection relays and SER / DR system vide Lr.CE/P&C/SE/D/EEPC4/AEE3/F.TECH/D.27/17 Dated: 05.10.2017. To get administrative approval budgetary offer has bar protection relay from various companies ----Pending 3). SRPC vide Lr: SRPC/SE- III/CEA/2017/6450/DT:27.10.2017 gives features of SER/DR. Budgetary offer will be called for SER / DR having above features. ---Penidng
Review Meeting dated 19.12.2017: 2) & 3) The issue was discussed and TANGEDCO was asked to provide time-line for implementing the recommendations.
Mail dated 29.01.2018: Procurement work is under progress and will be completed by December 2018.
Review Meeting on 21.12.2018: TANTRANSCO informed that Tender would be floated by January 2019 and Procurement is expected by APril 2019. Works would be completed by December 2019.
Review meeting on 27.06.2019: 2. Tender issued. Timline- July 2020. 3. Tender has to be issued. Timline- July 2020. Mail dated 18.07.2019 2) Tender has been lodged two times. New indent was reaised on 06.07.19. and tender floating is expected by August 2019. 3) Tender has been lodged on 15.07.19 and new indent would be raised for the same shortly.
TANGEDCO mail dated 17.12.2019 and 12.02.2020: 2) e - tender has been opened on 26.11.19 and placing of purchase order is expected by January 2020. 3) New Indent was raised on 26.08.19 and procurement is undr progress.
TANGEDCO mail dated 12.02.2020: 2)For busbar protection relays: Placing of purchase order is expected by the end of this month and delivery period is 80 days from the date of issuing of PO.After the supplying of materials, the replacement work will be taken up during possible 230kV Bus LC. --Pending 3) For Stanalone Disturbance Recorder: Specification approval has been sought from our HQ for floating of the tender on 23.12.2019. Again,Reply was sent on 03.02.2020 for the clarification raised by HQ. After obtaing of the approval from HQ, tender will be floated. - Pending
TANGEDCO mail dated 28.11.2020: 2.) 3 nos. electromechanical relays were replaced with M/s Siemens make high impdedance differential relays and commissioned on 25.11.2020 in Bus A, Bus B and check zone.Balance 03 nos. of relays will be replaced in due course. 3). e-tender opening date is resheduled on 05.12.2020 .
50/I/3 Complete outage of 230kV 21-12-2015 at Busbar protection got operated for a fault in 230kV TANTRANSCO to examine the feasibility of providing two main-zone operation TANTRANSCO TANTRANSCO Mail received on 19-02-2016 and 24-03-2016: Pending Mywadi station of 6:28 hrs Mywadi-Anaikadavu line for bus bar protection by exploring various alternatives like replacing existing Revision of Bus Bar Protection setting was carried out. The stabilizing voltage TANTRANSCO bus-coupler CB with a hybrid bus-coupler CB that comes with inbuilt CT, setting was raised from 410 to 450 volts. After completing the necessary test, the replacing existing BBP relay with another suitable relay that supports two main- bus bar protection put in to service on 29.12.2015. zone operation, and implement the same. Mail Received on 27-04-2016 ,16-06-2016,25-07-2016 & 24-09-2016: Revision of Bus Bar Protection setting was carried out. After completing the necessary test, the bus bar protection put in to service on 29.12.2015. Mail received on 10-11-2016 & 20.12.2016: Provision of Bus Coupler bay arrangement was included in the Upgradation works proposed and the same was sanctioned by MoP through PSDF. Numerical relay allotted and being commissioned. Mail received on 20-02-2017: Numerical BBP relay was commissioned on 02.02.2017 Page 35 of 52 50/I/3 Complete outage of 230kV 21-12-2015 at Busbar protection got operated for a fault in 230kV TANTRANSCO to examine the feasibility of providing two main-zone operation TANTRANSCO Pending Mywadi station of 6:28 hrs Mywadi-Anaikadavu line for bus bar protection by exploring various alternatives like replacing existing TANTRANSCO bus-coupler CB with a hybrid bus-coupler CB that comes with inbuilt CT, replacing existing BBP relay with another suitable relay that supports two main- zone operation, and implement the same.
Annexure-C Status received vide mail dated 18-09-2017 & 31-20-2017: Numerical BBP relay was commissioned on 02.02.2017. Provision of CT in Bus Coupler bay is arranged and zone segregation will be provided. Status received vid email dated 12-12-2017: Numerical BBP relay was commissioned on 02.02.2017. Provision of CT in Bus Coupler bay has been allotted. Zone segregation will be provided after commissioning of CT. Review Meeting dated 19.12.2017: TANTRANSCO informed that the recommendation would be complied with by Status received vid email dated 11-12-2018: Civil work completed & CT will be commissioned after strengthening Bus .2 conductor jumpers.Awaiting Bus LC Time line before January 2019.
TANTRANSCO MAIL DATED 23.01.2019: Erection under progress will be completed before 31.01.2019 TANTRANSCO MAIL DATED 19.03.2019: Buscoupler bay will be commissioned by June 2019
TANTRANSCO MAIL DATED 13.06.2019: Buscoupler bay configuation in BBP will be completed by June 2019. Bus segregation will be ensured by 31.12.2019 after attending Isolator status feedback.
TANTRANSCO MAIL DATED 18.07.2019: Buscoupler bay configuation in BBP will be completed by June 2019. Bus segregation will be ensured by 31.12.2019 after attending Isolator status feedback.
TANTRANSCO mail dated 12.02.2020: Busbar protection with Zone segregation work have been completed . Double bus operation can be done after strengthening of bus (Twin Moose to Quad Moose). Time line requested upto 30.06.2020.
TANTRANSCO mail dated 20.05.2020 & 07.07.2020 & 28.09.2020 & 11.11.2020: Busbar protection with Zone segregation work have been completed . Double bus operation can be done after strengthening of bus (Twin Moose to Quad Moose). Time line requested upto 31.12.2020.
TANTRANSCO mail dated 18.01.2021: Strengthening of bus (Twin Moose to Quad Moose) programmed on 24.01.2021 Time line requested upto 31.01.2021. for implementation of double bus operation
55/I/1 Complete outage of 230 kV 12-05-2016 at Flashover of Auto Transformer- 2 HV TANTRANSCO to take steps to provide double-bus operation at their 230 kV TANTRANSCO Mail recieved on 25-07-2016 & 24-09-2016: Pending (GD) Gummidipoondi Station of 12:15 hrs B-phase Isolator supporting insulator of 230kV Gummidipoondi SS. TANTRANSCO: Auto Transformer-2 HV side Bus isolator 'C'-phase support TANTRANSCO Southern Bus occurred at Gummidipoondi station. insulator of 230kV Southern Bus was replaced and Bus Bar Protection scheme At the time of fault, Bus bar protection relay was not was restored on 12.05.2016. in service for pre-commissioning testing of Auto Status received vide mails received on 10-11-2016 & 20.12.2016 & 12.04.2017 Transformer-2. All feeders got tripped due to & 01.06.2017 & 15-06-2017 & 04.08.2017 & 18.09.2017: operation of zone-2 protection from remote ends. CT is not available in the Bus Coupler bay for zone segregation. CT latch relay is to be provided for all bays for zone segregation.
Status received vide mails received on 31-10-2017 & 12-12-2017: Numerical Bus bar protection panel allotted and will be commissioned with zone TANTRANSCO MAIL DATED 22.05.2018 & 08.06.2018: Numerical Busbar protection relay commissioned on 14.05.2018 TANTRANSCO MAIL DATED 23.07.2018: Control & Status of isolator feedeback to be provided by replacement of Drive Mechanism box. TANTRANSCO MAIL DATED 29.08.2018: Control & Status of isolator feedeback to be provided by replacement of Drive Mechanism box. TANTRANSCO MAIL DATED 11.09.2018: Control & Status of isolator feedeback to be provided by replacement of Drive Mechanism box. Timeline requested upto Dec 2018.
Status received vid email dated 11-12-2018: 1. TANTRANSCO: Estimate sanctioned for replacement of defective isolator status feedback. Work under progress. Lightning mask work under progress will be completed within three days.
Review Meeting on 21.12.2018: TANTRANSCO informed that Double bus operation would be provided by March, 2019.
TANTRANSCO MAIL DATED 23.01.2019: Isolator status will be ensured by March 2019
Page 36 of 52 55/I/1 Complete outage of 230 kV 12-05-2016 at Flashover of Auto Transformer- 2 HV TANTRANSCO to take steps to provide double-bus operation at their 230 kV TANTRANSCO Pending (GD) Gummidipoondi Station of 12:15 hrs B-phase Isolator supporting insulator of 230kV Gummidipoondi SS. TANTRANSCO Southern Bus occurred at Gummidipoondi station. At the time of fault, Bus bar protection relay was not in service for pre-commissioning testing of Auto Transformer-2. All feeders got tripped due to operation of zone-2 protection from remote ends.
Annexure-C TANTRANSCO MAIL DATED 19.03.2019: New 230kV isolators have been allotted for replacement of defective isolators. Hence time line requested upto June.2019. TANTRANSCO MAIL DATED 13.06.2019 & 18.07.2019: New 230kV isolators have been allotted for replacement of defective isolators. Hence time line requested uptoSep.2019 TANTRANSCO MAIL DATED 12.02.2020: New 230kV isolators have been allotted for replacement of defective isolators. Time line requested upto March 2020.
TANTRANSCO mail dated 20.05.2020 & 07.07.2020 & 28.09.2020: New 230kV isolators have been allotted for replacement of defective isolators. Time line requested upto 31.12 2020.
TANTRANSCO mail dated 18.01.2021: It is programmed to avail LC in Gummidipoondi bus on 26.01.2021 to Check the alignment of bus selection isolators. Further action is being taken to rectify / replace the sluggish 230kV Isolators in the bus coupler breaker and double bus operation will be bring into service before 31.03.2021.
Page 37 of 52 Annexure-C 58 Different type and Make of distance protection relays to be provided for Main-I & Main-II protection for 230kV feeders at 400 kV Sunguvarchathiram & 230 kV Sunguvarchathiram TANTRANSCO The issue was discussed in PCSC-58 meeting held on 18.10.2016, when PCSC Pending Substation [Carry-Over from Protection Audit Recommendations] forum agreed to de-link the implementation of the Item from the scope of (Requested to Protection Audit Recommendations (PAR), and pursue it as part of PCSC drop) Recommendations.
Status received vide mails dated 10.01.2017 & 12.04.2017 & 01.06.2017 &15- 06-2017 & 04.08.2017 & 18.09.2017 & 31-10-2017& 12-12-2017: Different make Relays will be provided for Main-I & II relays at Sunguvarchatram end in a phased manner.
TANTRANSCO MAIL DATED 22.05.2018: TANTRANSCO informed that the recommended works of providing different make Relays for Main-I & Main-II are targeted to be completed by September, 2018.
TANTRANSCO MAIL DATED 08.06.2018: provision of Different make Relays for Main-I & Main-II will be completed by September, 2018.
TANTRANSCO MAIL DATED 23.07.2018: Different make Relays will be provided for Main-I & II relays at Sunguvarchatram end in a phased manner. Timeline: September-2018.
TANTRANSCO MAIL DATED 29.08.2018 & 11.09.2018: Different make Relays will be provided for Main-I & II relays at Sunguvarchatram end in a phased manner. Timeline: September-2019.
TANTRANSCO MAIL DATED 11-12-2018: Different make Relays will be provided for Main-I & II relays at Sunguvarchatram end in a phased manner. Timeline: September-2019
TANTRANSCO MAIL DATED 23.01.2019: Different make Relays will be provided for Main-I & II relays at Sunguvarchatram end in a phased manner. Timeline: September-2019. TANTRANSCO MAIL DATED 13.06.2019 & 18.07.2019: Different make Relays will be provided for Main-I & II relays at Sunguvarchatram end in a phased manner. Timeline: September-2019
TANTRANSCO MAIL DATED 12.02.2020: Different make Relays will be provided for Main-I & II relays at Sunguvarchatram end in a phased manner. Timeline: June 2020.
TANTRANSCO mail dated 20.05.2020 & 15.06.2020 & 28.09.2020 & 11.11.2020 & 18.01.2021: Since this subatation is SAS SS, the integration of other make relays attracts huge financial implication.Hence this recommendation may be dropped. So far there is no missing operation / other issues due to same make reay in this substation.
58/II/17 Multiple tripping at 230 kV 14-09-2016 at Bus Bar Protection (Zone-2) of 230 kV Bus-B got 1. TANTRANSCO to check the healthiness of BBP relay by conducting stability TANTRANSCO Mail received on 10-11-2016 & 20.12.2016: Pending Alamathy Station 11:13Hrs operated at Alamathy Station during fault in 230 kV test, and take appropriate remedial action like increasing voltage settings, 1. The Bus Bar Protection scheme will be tested for healthiness including the CT Alamathy-Korattur feeder. ensuring the healthiness of CT’s, using CT’s with similar characteristics (equal circuits. saturation effects & equal winding resistances) etc. at their 230 kV Alamathy 2. High impedance BBP relay will be replaced by Numerical relay. SS. Status received vide mails dated 10.01.2017 & 12.04.2017 & 01.06.2017 & 15- 06-2017: 2. TANTRANSCO to replace the existing high-impedance BBP relay with its 1. The Bus Bar Protection scheme was tested for healthiness including the CT low-impedance/ numerical variant so as to accommodate variation in CT circuits. AREVA make CTs in Alamathy SS are having different kneepoint characteristics at their 230 kV Alamathy SS. voltage for the cores. CT cores of higher knee point voltage has been choosen for BBP in 230kV Korattur, 230kV OPG-1 & 230kV OPG-2 feeders on 29.11.2016. -- -- Completed.
2. High impedance BBP relay will be replaced by Numerical relay. --- Pending,
15-09-2016 at Bus Bar Protection (Zone1) of 230kV Bus-A got Status received vide mails dated 04.08.2017 & 18.09.2017 & 31-10-2017 & 12- 22:14 hrs operated at Alamathy Station during fault in 230 kV 12-2017. Alamathy-OPG-1 feeder. 1. ---- Completed 2. High impedance BBP relay will be replaced by Numerical relay. --- Pending
Review Meeting dated 19.12.2017: 2) TANTRANSCO informed that Numerical BBP would be provided by April, 2018 --- Pending TANTRANSCO mail received on 25-01-2018: 1. --- Complied. 2. High impedance BBP relay will be replaced by Numerical relay. Timeline: April-2018.
TANTRANSCO MAIL DATED 22.05.2018 & 08.06.2018 & 23.07.2018: 2.Numerical BBP relay will be provided. Timeline: Sep-2018.
TANTRANSCO MAIL DATED 29.08.2018 & 11.09.2018: 1. Complied
Page 38 of 52 58/II/17 Multiple tripping at 230 kV 1. TANTRANSCO to check the healthiness of BBP relay by conducting stability TANTRANSCO Pending Alamathy Station test, and take appropriate remedial action like increasing voltage settings, ensuring the healthiness of CT’s, using CT’s with similar characteristics (equal saturation effects & equal winding resistances) etc. at their 230 kV Alamathy SS.
2. TANTRANSCO to replace the existing high-impedance BBP relay with its low-impedance/ numerical variant so as to accommodate variation in CT characteristics at their 230 kV Alamathy SS.
15-09-2016 at Bus Bar Protection (Zone1) of 230kV Bus-A got 22:14 hrs operated at Alamathy Station during fault in 230 kV Alamathy-OPG-1 feeder.
Annexure-C TANTRANSCO MAIL DATED 11-12-2018 & 23.01.2019: Numerical BBP relay to procured. Timeline: Sep-2019.
TANTRANSCO MAIL DATED 19.03.2019 & 13.06.2019 & 18.07.2019: Numerical BBP relay to be procured. Timeline: Sep-2019.
Review meeting on 27.06.2019: Timeline requested upto July 2020.
TANTRANSCO MAIL DATED 12.02.2020: Timeline requested upto July 2020.
TANTRANSCO MAIL DATED 29.05.2020 & 07.07.2020 & 28.09.2020 & 11.11.2020 & 18.01.2021: Numerical relay procurement under progress
Page 39 of 52 Annexure-C 64/1/4 Complete outage of North 26-03-2017 Tripping of evacuating lines due to fault led to 1. TANTRANSCO to take steps to complete insulator replacement works on the TANTRANSCO Status received vide mails dated 04.08.2017 & 18.09.2017 & 31-10-2017: Pending Chennai TPS STG-1 at 23:14hrs tripping of running Unit at NCTPS Stg-1 230 kV lines owned by them in NCTPS area within 6 months. 1. All the Porcelain insulators were replaced with Polymer insulators in 230kV NCTPS-I - Tondiarpet feeders - 1 & 2. 2. TANTRANSCO to take steps to implement A/R on all 230 kV lines ---- Completed emanating from NCTPS-I at the earliest. 2. AR will be implemented on all 230kV lines emanating from NCTPS-I. --- Pending
Status received vid email dated 12-12-2017: 1. Completed 2. The scheme needs modification to enable AR, since AR was not envisaged for this station during commissioning. AR will be implemented on all 230kV lines emanating from NCTPS-I within six months. --- Pending
Review Meeting dated 19.12.2017: 2) TANTRANSCO informed that A/R would be implemented on all 230 kV lines emanating from NCTPS-I by June, 2018.
TANTRANSCO mail received on 25-01-2018: 1. Complied. 2. The scheme needs modification to enable AR, since AR was not envisaged for this station during commissioning. AR will be implemented on all 230kV lines emanating from NCTPS-I within six months. Timeline:June-2018.
TANTRANSCO MAIL DATED 22.05.2018: 2. The scheme needs modification to enable AR, since AR was not envisaged for this station during commissioning. AR will be implemented on all 230kV lines emanating from NCTPS-I Timeline:Sep -2018.
TANTRANSCO mail received on 08-06-2018: 1. Complied. 2. The scheme needs modification to enable AR, since AR was not envisaged for this station during commissioning. AR will be implemented on all 230kV lines emanating from NCTPS-I Timeline:Sep -2018.
TANTRANSCO MAIL DATED 23.07.2018: AR implemented for 4 feeders and remaining lines will be provided with AR subsequently.
TANTRANSCO MAIL DATED 29.08.2018: 1. Complied 2. AR enabled for 3 feeders.
TANTRANSCO MAIL DATED 11.09.2018: 1. Complied 2. AR enabled for 5 feeders.
TANTRANSCO MAIL DATED 11-12-2018: 2. Enabling AR pending for 3 feeders. ( Sriperumpudhur end breaker problem, Tondiarpet & Alamathy feeder . static relay to be replaced. Timeline - 1 year
TANTRANSCO MAIL DATED 23.01.2019: Enabling AR pending for 3 feeders. ( Sriperumpudhur end breaker problem, Tondiarpet & Alamathy feeder . static relay to be replaced. Timeline -Sep 2019
TANTRANSCO MAIL DATED 19.03.2019 & 13.06.2019 & 18.07.2019: Enabling AR pending for 3 feeders. ( Sriperumpudhur end breaker problem, Tondiarpet & Alamathy feeder . static relay to be replaced. Timeline -Sep 2019
TANTRANSCO MAIL DATED 12.02.2020 & 20.05.2020: 1. (i). Polymer insulators has been provided in all the 400 kV evacuation lines from NCTPS end up to 5 KMs. Replacement of Polymer insulator in 230 kV lines are under progress for the 230 kV lines emanating from NCTPS. 2. Enabling AR pending for 3 feeders. ( Sriperumpudhur end breaker problem, Tondiarpet & Alamathy feeder . static relay to be replaced. Since the CBs and the Control & Relay Panels (CRP) are very old and commissioned during 1993. The Distance relays even though are numerical due to ageing its display and resetting keys are faulty. Hence it is proposed to replace the CBs & CRPs with new CBs and Protection relay panel with SAS. A.R will be put into service after replacing the CB & CRP.
TANTRANSCO mail dated 07.07.2020 & 28.09.2020 & 11.11.2020: Enabling AR pending for 3 feeders. ( Sriperumpudhur end breaker problem, Tondiarpet & Alamathy feeder . static relay to be replaced. Since the CBs and the Control & Relay Panels (CRP) are very old and commissioned during 1993. The Distance relays even though are numerical due to ageing its display and resetting keys are faulty. Hence it is proposed to replace the CBs & CRPs with new CBs and Protection relay panel with SAS. A.R will be put into service after replacing the CB & CRP. .
TANTRANSCO mail dated 18.01.2021: 1. Insulator replacement (Polymer insulator in place of Porcelain Insulator) in all the 230 kV #s emanating from the NCTPS 230 kV Switchyard in the vulnerable areas has been completed. -- Complied 2. Pending
Page 40 of 52 Annexure-C 77/II/9 Multiple trippings at TANTRANSCO to refer the issue of selective tripping of 400 kV side breakers, TANTRANSCO mail dated 11.09.2018: Pending [ 400 kV Manali Substation and non-tripping of 230 kV side breakers due to operation of Densimeters on OEM will be referred Requested to low pressure in the instant case to their OEM, and share OEM’s advice/ remedy Review Meeting on 21.12.2018: drop] in this regard. TANTRANSCO was asked to update the status. TANTRANSCO MAIL DATED 23.01.2019, 19.03.2019 & 13.06.2019: The issue was referred with OEM & reply awaited. Review meeting on 27.06.2019: OEM reply shall be communicated by end of July 2019
TANTRANSCO mail dated 18.07.2019: The issue was referred with OEM & reply awaited
TANTRANSCO MAIL DATED 12.02.2020 & 20.05.2020: The issue was referred with OEM & reply awaited.
TANTRANSCO mail dated 11.11.2020: 1 No KAT relay of NR make provided in each NR relay panel for selected DC does not have a variable DC under voltage setting and sensing feature. Dc respective LCC panels are connected to thses relays.Minor voltage variatio in source.1 DC could not be sensed by these KAT relays. As result , the contactors for SF6 gas system monitoring in LCC panels TANTRANSCOdropout whenever mail DC dated voltage 18.01.2021: dips occur and thereby leads tripping of Issue has been referred to the OEM of GIS M/s. Hyosung Corporation and reminders also sent for advice/ remedy in this regard. But the OEM not yet furnish their remarks.
Further the happening of drop of 220 V Station DC below thresh hold was due to non availability of Station AC supply for longer time. Only one Station AC supply source was available at that time.
Second Station AC source from different TANGEDCO station has been commissioned and 125 KVA DG set also has been commissioned. Hence it is confirmed that above issue will not be repeated. Hence request to drop this point.
79/I/3 Complete outage of 230 kV 05-10-2018 at Bus-1 got tripped at 230 kV Thiruvalam substation TANTRANSCO to take steps to implement multi-bus, multi-zone operation TANTRANSCO TANTRANSCO MAIL DATED 11-12-2018: Pending [ Requested to drop] Thiruvalam Substation 14:32 hrs due to spurious LBB relay (independent) operation (Double-bus operation) at their 230 kV Thiruvalam SS by December, 2018. Due to space constraint, the equipments could not be erected. of 230kV Thiruvalam Chittoor line. 230kV Review Meeting on 21.12.2018: Thiruvalam substation was under single bus It was noted that the station was on a single (Main) bus and there was not even operation; hence operation of LBB protection transfer bus. In view of the importance of 230 kV Thiruvalam SS, resulted in tripping of all connected elements TANTRANSCO was asked to take steps to provide dobule-bus operation at their resulting in the complete outage 230 kV Tiruvalam SS.
TANTRANSCO MAIL DATED 23.01.2019 & 19.03.2019: Feasibility for providing hybrid breaker / shifting of bays will be studied & action will be taken. Time upto Sep 2019
TANTRANSCO MAIL DATED 13.06.2019 & 18.07.2019: Bus segregation will be ensured by providing bus coupler bay by extending the existing Bus.Time line 31.12.2019.
TANTRANSCO MAIL DATED 11.11.2019 and 12.02.2020 & 20.05.2020 & 07.07.2020 Bus segregation will be ensured by providing bus coupler bay by extending the existing Bus.Time line 31.12.2020.
TANTRANSCO mail dated 11.11.2020 & 18.01.2021: Due to inadequate space,it is not fesible to provide hybrid BC breaker.
82/I/1 Complete outage of 400kV 28-01-2019 Failure of ‘R-phase’ HV side Current transformer 1) TANTRANSCO to ensure proper legends for DR Digital signals and all TANTRANSCO TANTRANSCO MAIL DATED 13.06.2019: Pending Sriperumbudur station at 01:15 Hrs (CT) of 315MVA 400/230kV ICT-3 at 400kV required events(including CB status, Type of protection operated) are captured 1. At present Duobias relay avaiable I/O configuration could not be carried Sriperumbudur substation (400kV TANTRANSCO in Event logger. out.after changing the relay Digital signals will be configured switchyard). 2) TANTRANSCO to extend BBP trip from BusBar relay to 86A (with source-1 2.COMPLIED DC) in addition to 86B (with source-2 DC), or to provide Common trip relay 96 3.Provision of Numerical BBP relay covered under R&M work. Tender under with redundant DC supply. progress. 3) TANTRANSCO to inform the action plan with timelines for providing 4.out of 30 CTs, 21 No CTs have been replaced with new one. Numerical BBP at Sriperumbdur SS . 4) TANTRANSCO to check the healthiness of all CT’s in the stationand submit Review meeting on 27.06.2019: a report regarding the same to SRPC to prevent any such occurrence in future. 1. , 3. Timeline requested upto July 2020. 2. Complied 4. Timeline requested upto September 2019.
TANTRANSCO mail dated 18.07.2019: 1. At present Duobias relay avaiable I/O configuration could not be carried out.after changing the relay Digital signals will be configured 2.COMPLIED 3.Provision of Numerical BBP relay covered under R&M work. Tender under
Page 41 of 52 82/I/1 Complete outage of 400kV 28-01-2019 Failure of ‘R-phase’ HV side Current transformer 1) TANTRANSCO to ensure proper legends for DR Digital signals and all TANTRANSCO Pending Sriperumbudur station at 01:15 Hrs (CT) of 315MVA 400/230kV ICT-3 at 400kV required events(including CB status, Type of protection operated) are captured Sriperumbudur substation (400kV TANTRANSCO in Event logger. switchyard). 2) TANTRANSCO to extend BBP trip from BusBar relay to 86A (with source-1 DC) in addition to 86B (with source-2 DC), or to provide Common trip relay 96 with redundant DC supply. 3) TANTRANSCO to inform the action plan with timelines for providing Numerical BBP at Sriperumbdur SS . 4) TANTRANSCO to check the healthiness of all CT’s in the stationand submit a report regarding the same to SRPC to prevent any such occurrence in future.
Annexure-C TANTRANSCO mail dated 11.11.2019 and 12.02.2020: 1. At present Duobias relay avaiable I/O configuration could not be carried out.after changing the relay Digital signals will be configured 2.COMPLIED 3.Provision of Numerical BBP relay covered under R&M work. Tender under progress. 4.out of 3 CTs, 27 No CTs have been replaced with new one.
TANTRANSCO mail dated 20.05.2020 & 07.07.2020 & 11.11.2020: 1. At present Duobias relay avaiable I/O configuration could not be carried out.after changing the relay Digital signals will be configured 2.COMPLIED 3.Provision of Numerical BBP relay covered under R&M work. Tender under progress. 4.out of 30 CTs, 27 No CTs have been replaced with new one. Time line requested upto 31.12.2020
TANTRANSCO maiil dated 18.01.2021: 1. At present Duobias relay avaiable I/O configuration could not be carried out. New relay allotted and awaiting for line clear . Time line requested upto 31.03.2021. 2.COMPLIED 3.Provision of Numerical BBP relay covered under R&M work. Tender under progress. 4.out of 30 CTs, 29 No CTs have been replaced with new one. One no of CT is kept pending due to oil leak.Time line requested upto 31.03.2021.
85/II/1 Tripping of 400/230kV 13-05-2019 at ICT-3 got tripped on the activation of HV REF 1. TANTRANCO is recommended to sort out the malfunctioning of ICT Ref TANTRANSCO TANTRANSCO mail dated 11.11.2019: Pending MANALI ICT-3 2:42 hrs protection. During test charging of 110 kV Manali- protection in consultation with OEM and submit a detailed report regarding the 1. The issue was addressed to OEM reply awaited. ETPS -1 , the 110 kV ETPS -1 got tripped on the same in 1 month time. 2. Uniform Labelling of Digital signal will be ensured. activation of Back up relay and Distance relay failed 2. TANTRANSCO is recommended to ensure proper labelling of all digital to act signals in Disturbance recorders of lines and ICTs at Manali SS. TANTRANSCO mail dated 12.02.2020: 1. The issue was addressed to OEM reply awaited. 2. Proper labeling of D.R has been implemented.
TANTRANSCO mail dated 20.05.2020 & 07.07.2020 & 28.09.2020 & 11.11.2020 & 18.01.2021: 1. The issue was addressed to OEM reply awaited. 2. Complied
89/II/2 Tripping of 400/230 kV ICT-2 at 28-11-2019 at 10:43 • 400 kV SVC SS-ICT2- R phase tripped on percentage TANTRANSCO TANTRANSCO mail dated 20.05.2020: Pending Sungavarchatram SS of Hr. Differential & REF protection. will be complied TANTRANSCO • During test charging of 110 KV Oragdam-SP Koil-1# at 230 KV Oragadam SS the feeder got tripped on SOTF due to R TANTRANSCO mail dated 14.07.2020 & 28.09.2020 & 11.11.2020 & 18.01.2021: phase CT blast. OEM has reported that the misbehave of LVCT at ICT2 leads tripping. Action is being taken to i. TANTRANSCO to test all CTs (secondary voltage measurement and Tandelta measurement) replace the same. Timeline requested upto 31.12.2020 and replace if CTs found mal-operating. CT cable also needs to be tested. ii. TANTRANSCO to furnish the OEM findings regarding the tripping at the earliest .
90/I/5 Complete Outage of 230kV 12-03-2020 at 01:20 Triggering incident was failure of Y phase CT of Bus Coupler • TANTRANSCO to ensure due care regarding the settings and wirings so that trip signal is TANTRANSCO TANTRANSCO mail dated 11.11.2020: Complied Checkanurani SS of Hr. at 230kV Checkanurani SS. Bus-1 and Bus-2 Busbar Protection extended from TANTRANSCO BBP to PGCIL ICTs, in future. Will be ensured. TANTRANSCO operated resulting in the tripping of all connected elements. However, ICT#3 was not tripped. Since the failed CT was near TANTRANSCO mail dated 18.01.2021: Bus-1 side, due to non-tripping of ICT#3, which was connected Line clear was availed at 14.20Hrs (17.11.2020) and tested the Busbar protection relay. During the to Bus-2, there was no fault feed after the isolation of Bus-1. testing it was observed that output contact of Busbar protection trip relay pertaining to LV3 Subsequently, ICT#3 was hand tripped. found defective. The same was replaced with available spare contacts and actual tripping extended to LV3 at PGCIL end and found satisfactory
91/I/5 Complete outage of 19-04-2020 at • Triggering incident was YN fault in 230kV Karaikudi- i. TANTRANSCO to avoid single bus operation at their Substations where atleast 2 buses are TANTRANSCO TANTRANSCO vide mail dated 28.09.2020 & 11.11.2020: Pending 230kV/110kV Karambyam SS 04:14Hrs Karambyam line. available. Due to Isolator feed back problem, the single bus operation has been maintained and Multiple Tripping in • At the same time, bus fault occurred at 230kV Thiruvarur SS ii. To share the reasons for SLDC instruction for single bus operation at Tiruvarur. 230kV/110kV Thiruvarur SS of due to snapping of B phase dropper conductor of 230 kV TANTRANSCO mail dated 18.01.2021: TANTRANSCO Thanjavur-Thiruvarur line near Bus-1 side isolator and Bus-1 Due to Isolator feed back problem, the single bus operation has been maintained. Action is being BBP operated resulting in the tripping of all the elements taken to implememt the double bus operation Time line requested upto 30.06.2021 connected to 230kV Thiruvarur SS. • Since 230kV Thiruvarur SS was under single bus operation, this resulted in de-energization of 230kV bus at Thiruvarur SS. 92/1/I Complete outage of 230kV 22-06-2020 at 23:47 • During antecedent conditions, 230kV Mwyadi SS was under i. TANTRANSCO to expedite the process of Bus strengthening at 230kV Mywadi SS, on priority , TANTRANSCO TANTRANSCO mail dated 11.11.2020: Pending Mywadi substation of Hr. single bus operation. in order to restore double bus operation. Healthiness of other CTs in the SS shall also be 1. Busbar protection with Zone segregation work have been completed . Double bus operation can TANTRANSCO • Triggering incident was failure of B phase CT of 230kV ensured. be done after strengthening of bus (Twin Moose to Quad Moose). Time line requested upto Mywadi-Ponnapuram line-2 at 230kV Mywadi end. ii. TANTRANSCO requested to submit equipment failure report to CEA with a copy to SRPC. 31.12.2020 • 230 kV Bus-1 bus bar protection operated resulting in the 2. tripping of all the connected elements at 230kV Mywadi. • 400kV/230kV Udumalpet ICT-1, 2 and 3 also tripped during TANTRANSCO mail dated 18.01.2021: the event. Strengthening of bus (Twin Moose to Quad Moose) programmed on 24.01.2021 Time line requested upto 31.01.2021. for implementation of double bus operation
92/II/3 Tripping of 400/110kV, 09-06-2020 at • 400/110kV, 200MVA ICT No.3, 4 and 5 at Kanarpatty TANTRANSCO to plan for augmentation of transformer capacity at 400kV Kanarpatti SS to TANTRANSCO TANTRANSCO mail dated 11.11.2020: Complied 200MVA ICT-3,4,5 at 11:13Hr. tripped on over current protection due to overloading of the overcome the issue of overloading of transformers and violation of (n-1). Augumentation of Transformer capacity will be ensured after conducting system studies -- Kanarpatty ICTs. Complied • As reported by TANTRANSCO there was wind generation variation during the event. From the SCADA data available at SRLDC antecedent flows recorded were ICT-3 = 179MW, ICT- 4 = 181 MW and ICT-5 = 180MW.
Page 42 of 52 Annexure-C 94/I/13 Complete Outage of 400k V 05-Dec-20 As per the information received, connected 400kV lines tripped i. OVR protection signals (Start & Trip for both Stage-I & Stage-II) are to be properly configured TANTRANSCO Yet to be informed Pending SPIC Energy Power Corporation 02:48 hrs on operation of OV St-1 protection resulting in complete loss of in DRs & ELs of protection relays of all 400 kV lines by TANTRANSCO. (SEPC) supply at 400kV SEPC ii. TANTRANSCO to configure OVR operation to send DT to remote end, and to maintain healthiness of communication channel of 400kV SEPC - Thenampatty lines to ensure proper DT communication.
94/II/13 Tripping of 400/230kV ICT#2 at 01-Nov-20 ICT#2 and 400kV Alamathy -Thiruvalam line-2 are in the same i. TANTRANSCO to enable A/R for both Main-CB & Tie-CB in all dias where one of the elements TANTRANSCO Yet to be informed Pending Tiruvalam 10:57 hrs dia at 400kV Thiruvalam end. During antecedent conditions, is a transmission line at their 400/ 230 kV Thiruvalam SS. Main breaker of ICT#2 at Thiruvalam end was under outage ii. TANTRANSCO to configure OVR start and OVR trip in DR/ EL of the protection relays of all 01-Nov-20 due to CT replacement works. Triggering incident was R phase 400kV transmission lines emanating from their 400/ 230 kV Thiruvalam SS 12:17 hrs to Earth fault in 400kV Alamathy -Thiruvalam line-2. A/r operated successfully at both the ends and line was holding. At 02-Nov-20 Thiruvalam end, A/R of main breaker only operated and tie 11:32 hrs breaker tripped. Due to tripping of tie breaker at Thiruvalm end, ICT#2 also tripped 25-Nov-20 21:26 hrs 94/II/23 Tripping of 230 kV Bus-1 at 230/ 17-Nov-20 Triggering incident was BE fault in 230kV Trichy TN - TANTRANSCO to take steps to provide multi-bus operation at their 230 kV Trichy SS. TANTRANSCO Yet to be informed Pending 110 kV Trichy-TN SS of 00:01 hrs Alandur line-1. Due to non-opening of breaker at 230kV Trichy TANTRANSCO TN end, LBB operated resulting in the tripping of all the elements connected to 230 kV Bus-1 at 230kV Trichy TN SS.
Page 43 of 52 Annexure-C
PED
Kerala
58/I/1 Complete outage of 220 kV 23-08-2016 Triggering incident was conductor snapping in 110 KSEB to take steps to provide the following at their 220/ 110 kV Kalamassery KSEB KSEB Mail received vide dated 17.01.2017: Pending (GD) Kalamassery Substation at 11:20 hrs kV Kalamassery- Kaloor feeder SS: 1. 110 kV bus bar protection progressing ----Pending 1. Busbar protection at 110 kV level 2. Connection of 220kV earth mat and 110 kV plate earthing system completed.--- - Completed 2. Connecting 220 kV and 110 kV sides on to a common earthmat 3. Redundancy of 110V DC system in progress. Complete independent redundancy is not practical for the time being. 48 V DC redundancy was already 3. Redundant DC supply for both protection (220 V) and communication (48 V) there. ----Pending applications 4. Instead of stand alone event logger, SCADA system of 110 kV feeder is expected to be completed by the end of 2017. SCADA system of 220kV side will 4. Stand-alone Event Logger be taken up after that ----Pending
KSEB Mail received vide dated 18.09.2017: 1. 110 kV bus bar protection is under progress --- Pending 2. --- Completed 3. Redundacny of DC supply for both 110kV and 48v. Provided separate DC Status received vide mail dated 12-12-2017: 1. Detailed engineering of the scheme has been completed. Material procurement is in progress. ---Pending 2.,3. ---- Completed 4. The SOE and DR are available with time stamping from the numerical relays. Hence stand alone event logger is not necessary ----- Completed
Status received vide mail dated 11-12-2018: Work has been already tendered. It is expected that purchase process will completed within three months.
Status received vide mail dated 17.01.2019: At the time of bid only one bidder participated and the work has been retendered.
Status received vide mail dated 19.03.2019: Status as on 18.03.2019: Based on the retender, have received two offers from 1) GE T&D Ltd 2)Consyse . The offer from GE T&D is found to be technically acceptable.But the rate received is above PAC and the request has been submitted to CE ( Trans South ) for sanction to issue purchase order.
Status received vide mail dated 03.05.2019: Sanction to issue purchase order in progress. Time Frame is January 2020 .
Review meeting on 27.06.2019. 1. BBP will be commissioned by December 2019. 2.,3.,4. Completed
KSEBL mail dated 16.12.2019: 1)The station authorities have already initiated action to implement the same by June 2020. 2.,3.,4.KSEBL Completed mail dated 01.08.2020: The work, 'Commissioning of the bus bar protection system of 110 kV Bus at 220kV SS Kalamassery' is in progress. Panel erection completed. Construction of yard cubicles completed. Control cable laying completed. Sectionalizer and bus coupler work is in progress. Expected date of commissioning 30.09.2020
Page 44 of 52 Annexure-C 79/I/1 Complete Outage of 220 kV 01-10-2018 at Triggering incident was R-Ph fault in 220kV Idukki- 1). KSEBL to check & correct the LBB time setting employed at their Idukki PH KSEBL Status received vide mail dated 11-12-2018: Pending Idukki Power Station 04:16 hrs Kalamassery line-2. R-phase pole of breaker didn’t to 200 msec. 1) Present setting is 180ms.OEM(ABB) suggests that it will give around 200ms open at Idukki end. LBB of Bus-2 operated resulting delay as it is having inherent delay is of around 20ms(ie, 180ms +20ms in tripping of all connected elements along with 2). KSEBL o ensure that DR’s & EL’s of all Protection Relays (PR’s) at their =200ms).With this setting the fault clearence is found after 220ms.So further running Unit#4 at Idukki and 50MVA station Idukki PH are configured for recording all mandated protections & signals. revision may be carried out after discussion. transformer. At the same time, 220kV Idukki 2)Breaker status will be ready only after completing the GOOSE network as part Kalamassery line-1 also got tripped at Idukki end. of renovation of all feeder panels and Idukki first stage units by June 2019 . Subsequently running Units 1 and 2 also tripped on Governor oil Low Pressure due to loss of AC supply. Status received vide mail dated 03.05.2019: This resulted in complete outage of Idukki PS. 1) Pending..... 2)Breaker status will be ready only after completing the GOOSE network as part of renovation of all feeder panels and Idukki first stage units by January 2020 ....Pending KSEBL mail dated 15.01.2020 1. Completed 2)Breaker status will be ready only after completing the GOOSE network as part of renovation of all feeder panels and Idukki first stage units by March 2020 --- Pending
KSEBL mail dated 12.02.2020: 1) Completed 2)Breaker status will be ready only after completing the GOOSE network as part of renovation of all feeder panels and Idukki first stage units by June 2020.
80/II/5 Multiple trippings at 220 15-10-2018 at Triggering incident was Y-phase to ground fault in KSEBL to take steps to replace the existing static (high impedance type) 220 kV KSEBL Status received vide mail dated 11-12-2018: Pending kV Madakathra station 08:57 Hrs 220kV Madakathra – Palakkad_KL (Ellapully) line BBP with numerical Busbar protection at their 220 kV Madakathara SS. In progress due to flashover of pilot insulator string. Auto- reclose was successful at Madakathra end. At the Status received vide mail dated 19.03.2019: same time bus differential relay Zone-C mal- Status as on 18.03.2019: Estimate sanctioned by CE(Transmission North ) and operated resulting in tripping of all elements have prepared the technical specifications.Tendering procedures are yet to get connected to the bus. started.
Status received vide mail dated 03.05.2019: At the time of bid only one bidder participitated and the work has been KSEBL mail dated 01.08.2020: MDCC issued for 220 kV BBP Panel to M/s N/R Energy India Ltd. Panel not yet arrived at site.Expecting Panel on or before 25.07.20 Additional Cable laying works in switch yard - 95% completed. The Bus Bar Protection is expected to be in serrvice on or before 25.09.2020
82/I/5 Complete Outage of 220kV 08-02-2019 at Complete outage of 220kV Brahmapuram SS 1) KSEBL to furnish detailed report regarding the healthiness of BBP operation KSEBL Status received vide mail dated 03.05.2019 & 11.202.2020: Pending Bhramapuram substation of 10:28 hrs occurred due to suspected mal operation of Bus Bar at 220kV Brahmapuram after testing of the same on 12th April 2019. 1) Detailed report sent on 02.05.2019…..Completed. KSEB protection. 2) KSEBL to submit the action plan regarding 2) As reported earlier in this regard, the permanent solution to this problem is to (i) Replacing of the Static High impedance BBP (using CRM relays) with replace the existing high impedance static relay with a low impedance numerical Numerical BBP. relay. The station authorities have already initiated action to implement the same (ii) Replacement of CRM relays and relays with no Disturbance recording by June 2020. facilitites. KSEBL mail dated 01.08.2020: The work is included in 220kVSAS integration.The work is tendered .To be completed on 31.12.2020
84/I/3 Complete outage of 220 kV 27-05-2019 at Triggering incident was three phase to earth fault in 1.KSEBL may develop proper operational code for procedures to be followed KSEBL KSEBL mail dated 30.07.2019: Pending Edamon SS of KSEB 12:30 hr. 220 kV Edamon Bus 1 and 2. Bus 1 and 2 Bus bar while performing operations in switchyard and sensitize their operators to reduce 1. proper operrational code is avilalable in 220kV SS Edamon protection operated resulting in the tripping of all operational errors. 2.ksEBL to ensure time synchronization of relays at 2. All 220KV relays of Edamon substation are synchronized with GPS clock . Out connected elements. 220 kV Edamon SS. of this, 3 relays are having hardware issues with time synchronisation switch . This problem will be resolved by August 2019 itself.
Page 45 of 52 84/I/3 Complete outage of 220 kV 27-05-2019 at Triggering incident was three phase to earth fault in 1.KSEBL may develop proper operational code for procedures to be followed KSEBL Pending Edamon SS of KSEB 12:30 hr. 220 kV Edamon Bus 1 and 2. Bus 1 and 2 Bus bar while performing operations in switchyard and sensitize their operators to reduce protection operated resulting in the tripping of all operational errors. 2.ksEBL to ensure time synchronization of relays at connected elements. 220 kV Edamon SS. Annexure-C KSEBL mail dated 16.05.2020: Have taken steps to rectify the hardware issue with the 3rd relay and will be completed by end of October 2020
87/II/14 Tripping of 400/220 kV 29-08-2019 at ICT-3 got tripped during testing of busbar protection KSEBL to submit a report after providing separate breaker failure relays for KSEBL KSEBL mail dated 16.12.2019: Pending ICT-3 at Trichur 16:32 hr ICT-3 and sorting out the time synchronization issues of relays at 400 kV 1) Relay purchase is expected to be completed by Feb 2020. Report will be Madakkathara SS. complted by March 2020. 2) GPS connection issues were resolved
KSEBL mail dated 11.02.2020: 1)Work will be completed by the end of June 2020 2) completed.
KSEBL mail dated 01.08.2020: 1) Procurement of relay under process.Expected to complete the work on or before 30.09.2020 2) completed.
88/II/1 Complete loss of supply at 220kV 03-11-2019 at 15:05 Triggering incident was bus fault at Bus-2 of 220kV Idukki 1. KSEBL to submit a report after detailed inspection of Busbar relay regarding reason for KSEBL KSEBL mail dated 11.02.2020: Pending Idukki GS of KSEB Hr. station. operation of checkzone during through fault. 1)It was noticed that Bus coupler CT input was wrongly connected to bus bar protection. Rectified • This led to operation of bus bar protection at Idukki resulting 2. KSEBL to ensure equal distribution of feeders on both buses to reduce supply interruption in the maloperation issues.Disconnected Bus coupler CT input to Busbar protection.Now working Ok. in complete loss of supply at Idukki station. case of BBP operation of one Bus. -- Completed 2) Instructions have already been conveyed 3. KSEBL to rectify time sync issue at 220kV Idukki GS. for equal distribution of feeders and generators in both buses. -- Completed 3)Time suncronization will be rectified after RMU of Idukki feeders & 1st stage generatos by June 2020. --Pending
KSEBL mail dated 01.08.2020: 89/1/5 Complete loss of supply at 220 08-01-2020 at 14:22 • Triggering incident was conductor snapping of 220 kV KSEBL to replace existing high impedance BBP and mal-operating check Zone relay with Low KSEBL KSEBL mail dated 16.05.2020: Pending kV Kanhirode, 220 kV Hr. Kanhirode – Ambalathara feeder. impedance BBP at 220kV Kanhirode SS. Work will be completed by the end of December 2020 Ambalathara, 220 kV Mylatty, • Bus bar protection at 220 kV Kanhirode SS operated resulting 220 kV Thaliparamba and 220 in tripping of all connected elements. kV Orkattery SS of KSEB • There was complete loss of supply at 220 kV Ambalathara, Mylatty, Thaliparamba and Orkattery SS of KSEB since these station were radially fed from 220 kV Kanhirode station.
89/II/1 Tripping of Bus-1 and Bus-2 at 26-11-2019 at 09:04 • Bus bar protection of Bus-1 operated resulting in tripping of KSEBL to expedite the process of providing numerical BBP in place of mal-operating CRM KSEBL KSEBL mail dated 16.05.2020: Pending 220 kV Brahmapuram station of Hr. all elements connected to Bus-1 at 220 kV Brahmapuram. relays at 220 kV Brahmapuram SS. Work will be completed by the end of December 2020 KSEB KSEBL mail dated 01.08.2020: The work is included in 220kVSAS integration.The work is tendered .To be completed on 31.12.20
91/I/3 Complete outage of 220kV 14-04-2020 at • Triggering incident was RN fault in 220kV switchyard of i. KSEBL to expedite the process of providing BBP and GPS time synchronization of relays at KSEBL KSEBL mail dated 06.09.2020: Pending Kattakada SS and Multiple 10:32Hrs Kattakada SS. 220kV Kattakada SS at an early date. 1)BBP Work will be completed by end of March 2021---- Pending Tripping in 220kV Pothencode • Both 220kV Pothencode-Kattakada line-1 & 2 tripped. ii. DRs at Pothencode & Kattakada to be configured for all zone pick up and blocking of DEF on GPS time synchronization issue resolved at 220kV SS Kattakada--Completed SS of KSEB • At the same time, 220kV/110kV 200MVA transformers 1, 2 distance pick up to be ensured at Pothencode SS relays. and 3 at Pothencode and 220kV/110kV 200MVA transformer# 2) DRs at Pothencode & Kattakada configured for all zone pick up-- Completed 1 at Kattakada also got tripped. • Tripping of 220kV Pothencode-Kattakada line-1 & 2 resulted KSEBL vide mail dated 11.09.2020 informed that: in complete loss of supply at 220kV Kattakada SS since it is i. Pending radially fed from Pothencode SS. ii. DEF at Katakada is configured in external relay and time delay is set as back up to 2nd zone of protected line and hence possibility of maloperation is very less. It will not act before distance protection.
94/I/1 Complete Outage of 220kV 01-Oct-20 Triggering incident was failure of R-phase CT connected to i. KSEBL to submit Equipment failure report for the failed CT to CEA with a copy to SRPC. KSEBL Yet to be informed Pending Sabarigiri GS of KSEB 18:06 hrs 220kV Sabaigiri - Edamon feeder-2. As reported LBB operated ii. KSEBL to revise LBB timings for all feeders at 220kV Sabarigiri GS to 200msec (existing and all connected elements tripped at Sabarigiri end only 250msec) and configure LBB operation for sending of DT to remote end. resulting in complete outage of 220kV Sabarigiri station. iii.End zone protection shall also be configured for all 220 kV lines at their 220 kV Sabarigiri GS.
PGCIL (SR-I & II)
Page 46 of 52 Annexure-C 85/II/16 Tripping of 400kV Tumkur- 29-05-2019 at Lines tripped due to Y-N & Y-B phase to earth fault PGCIL (SR-2) is recommended to submit Equipment failure report to CEA PGCIL (SR-II) Yet to be informed Pending Bidadi line-1&2, 400kV 6:11 hrs regarding the failed LA. Tumkur-Cuddapah line-2, 400kV Tumkur-Pavagada line-2
84/II/15 Tripping of 400kV Bus-1 25-04-2019 at 08:01Triggering hr. incident was failure of R-ph CB of bus 1. PGCIL (SR-II) was requested to send the equipment failure report to CEA. PGCIL (SR-II) PGCIL (SR-2) mail dated 16.12.2019: Pending and connected elements at reactor at 400kV Bidadi. Bus bar protection of Bus- 2.PGCIL (SR-II) is recommended to share the feedback of OEM regarding Report from OEM is yet to be received. 400kV Bidadi substation 1 operated resulting in the tripping of all elements decomposition of SF6 gas. connected to Bus-1
88/II/11 Tripping of 400kV Ramagundam- 16-10-2019 at 02:56 · Line tripped on operation of OV St-1 protection at N'Sagar 1. PGCIL-SR-1 to submit Event logger for the incidence clearly showing OVR_start and PGCIL-SR-I PGCIL-SR-1 mail dated 21.01.2021: Complied N’Sagar-1 Hr. end and DT was received at Ramagundam end. OVR_trip. 1. PGCIL-SR1: OVR start and OVR trip configured in relay event and same will be uploaded in • From DR of N'Sagar end, Vb-254kV. 2. PGCIL-SR-1 to check the OVR gradings adopted at 400kV N’Sagar SS. SRLDC trip portal for future O/V trippings. • Tripping is not as per OV grading at N'Sagar end. 2. PGCIL-SR1: OV grading given for Line-1 is 111% with 10 sec time delay & for line-2 is 110% with 8 sec time delay. At Nsagar site O/V settings of line-1 adopted in line-2 and vice versa. Due to this Line-1 tripped on O/V stg-1 ( Vb-254V). Site has interchanged the line-1 & line-2 O/V settings as per SRPC recommended settings after this tripping same was informed in 88th PCSC meeting.
90/I/4 Complete outage of 220kV Kolar, 09-05-2020 at During antecedent conditions, 220kV Kolar(Kar), 220kV PGCIL-SR-2 to submit justification regarding adopting Zone-2 timing of 100msec and Zone-3 PGCIL-SR-II Yet to be informed Pending 220kVMalur, 220kV Sarjapur 22:41Hr. Malur, 220kV Sarjapur and 220kV VikasTech Park (VTP) SS timing of 200msec on 220kV Kolar_PG Kolar_KA line. and 220kV VTP SS of KPTCL are radially fed from 220kV Kolar PG SS. Triggering incident was YB fault in220kV Kolar PG- Kolar(Kar) line-1. After tripping of 220kV Kolar PG-Kolar(Kar) line-1, 220kV Kolar PG-Kolar(Kar) line-2 got overloaded and tripped at Kolar(Kar) end due to operation of non-directional OC protection. Due to tripping of 220kV Kolar(PG)-Kolar(Kar) line-1 and 2, there was complete loss of supply at220kV Kolar(Kar), 220kV Malur, 220kV Sarjapur and 220kV Vikas Tech Park (VTP) SS
90/II/3 Tripping of 220kV Bus-2 at 22-03-2020 at 15:45 Triggering incident was failure of B-phase Lightning Arrester PGCIL-SR-1 to look into the directional O/C settings adopted for 400/220kV ICT-1 at PGCIL-SR-I Yet to be informed Pending 220kV Vizag switching station Hr. on 220kV VSS - Kakinada line. This resulted in operation of Gazuwaka, since its tripping for a Bus fault at 220kV VSS (cleared in time) on Directional O/C (VSS) of APTRANSCO Bus bar protection of bus-2 at 220kV VSS. 400/220kV, 315 protection was against the principle of coordinated protection system operation. MYA ICT-1 and ICT-2 also tripped during the incident.
90/II/20 Tripping of 220kV Kochi - 29-Dec-2019 at Triggering incident was failure of PT of 110kV Kalamassery - PGCIL-SR-2 to submit a detailed report on OEM findings related to the tripping PGCIL-SR-II Yet to be informed Pending Kalamaserry line-2 00:06:00 Hr. Carborandum line and CT failure of 110kV Kalamassery- Perumbavoor line at Kalamassery s/s end. 220kV Kochi - Kalamaserry line-2 tripped only at Kochi end on Zone 4 reverse operation. This needs review.
91/III/4 Tripping of 400kV 08-04-2020 • Triggering incident was B –N fault in the line. PGCIL(SR-1) to submit report regarding unsuccessful A/R attempt by tie breakers at PGCIL-SR-I PGCIL-Sr-1 mail dated 21.01.2021: Complied Maheshwaram – at 15:30Hrs • At Maheshwaram PG end, fault was sensed in Zone-1, A/r Maheshwaram end of the subject line and Remedial measures taken. Tie CB A/R not attempted due to goose signal configuration issue in Tie CB BCU and same was Narnoor line operated and line tripped due to subsequent fault during reclaim rectified. Main & Tie CB A/R scheme tested and found ok during the shutdown on 25.08.2020 time. Tie breaker didn't attempt A/r. • At Narnoor end, fault was sensed in Z1, initially B pole got opened but subsequently after 500ms, R and Y pole breakers also got opened and A/r not operated at Narnoor end.
94/I/2 Complete outage of 220/66 kV 06-Oct-20 Triggering incident was R -E fault in 66kV Feeder no-10 of PGCIL-SR2, in coordination with KSPDCL, to review Zonal settings of 220kV Pavagada – PGCIL-SR-II Yet to be informed Pending KSPDCL SS-6 (Pavagada) of 14:05 hrs KSPDCL SS-6. Feeder tripped on operation of Earth fault Thirumani line at Pavagada end. Further, the philosophy being followed for LDP relays at KSPDCL overcurrent protection. At the same time, 220kV Pavagada - pavagada end to be brought in line with the SRPC philosophy. Thirumani line-2 tripped only at Pavagada end on operation of Zone-1 distance protection. This resulted in complete outage of 220/66kV KSPDCL SS-6, since the only connected feeder tripped 94/I/10 Complete Outage of 220 kV 17-Nov-20 During antecedent condition, due to outage of 220kV PGCIL-SR2 to revise DEF settings of 220kV Kalamasserry – Kochi_PG such that DEF PGCIL-SR-II Yet to be informed Pending Kalamasserry SS of KSEB 12:41 hrs Kalamasserry - Idukki line-1 and 2, 220kV Kalamasserry SS protection will not operate for maximum expected load current under all operating scenarios. was radially fed from 400kV/220kV Kochi_PG SS and flows in Further, DEF should be kept blocked during DPR operation; and DEF should be enabled only 220kV Kochi_PG - Kalamasserry line-1 and 2 were around when DPR does not pick up. 195MW each respectively. As per the report submitted, triggering incident was B phase to Earth fault in 220kV Kochi_PG -Kalamasserry line-1. After the tripping of 220kV Kochi_PG -Kalamasserry line-1, 220kV Kochi_PG - Kalamasserry line-2 got overloaded. 220kV Kochi_PG - Kalamasserry line-2 tripped on operation of DEF protection as per IDMT curve at Kochi_PG end and was holding at Kalamasserry end.
Page 47 of 52 Annexure-C
Others
Page 48 of 52 Annexure-C 54/I/1 Complete outage of 230 kV 02-04-2016 at B-phase CT failure occurred in 230 kV S.P.Koil - 1.MAPS to furnish a detailed report on the tripping of SP Koil – MAPS lines 1 NPCIL (MAPS) Status revided vide MAPS mail dated 06.12.2016; Pending S.P.Koil Station of 17:08 hrs MAPS line-1. Busbar protection got operated at & 2 at MAPS end with focus on the correctness of the settings of Main-I & Main- 1. The settings given by M/s TANTRANSCO were adopted for Main –I & Main- TANTRANSCO SP.Koil station. All elements except 230kV II relays (for primary & back-up protections) on both the lines. II relays for both the lines. The same settings were verified to be same. Oragadam and 230kV Kalivandapattu got tripped at Subsequently calibrated was done and no drift was observed. --- Completed 230kV S.P.Koil station. ‘Y’ phase CT and support 2.MAPS to take steps to provide down-loading facility for DR & EL from Main-I insulators also got damaged. & Main-II relays on all 230 kV lines emanating from MAPS. 2. From May 2016 onwards, the DR, EL and trip report are being sent by mail to SRLDC, Bengaluru by MAPS. --- Completed 3.MAPS, in co-ordination with SP Koil, to carry out PLCC end-to-end testing, on SP Koil – MAPS lines 1 & 2, and ensure healthiness of PLCC 3. Monthly maintenance of PLCC equipments is being done by M/s communication & carrier-aided protection. TANTRANSCO. At present PLCC telephone is not working, it is being followed up. --- Completed 4.MAPS to put in service Auto-Reclosure feature on all four 230 kV lines emanating from MAPS by June, 2016. 4. CVTs are planned to be procured from M/s TANTRANSCO by the end of February 2017 and A/R will be implemented for all the lines emanating from MAPS by July-2017 as discussed in the current SRPC meeting on 25/11/2016. --- Pending
Status received vide MAPS mail dated 06.12.2016 & Review Meeting dated 19.12.2017; The CVTs procurement is in progress and the scheme (A/R) would be implemented before 31-03-2018.
Status revided vide MAPS mail dated 11.12.2018 The new CVTs were provided in all the three phases (R & B phases, CVTs were replaced and Y ph CVT was provided) of Line-1,2 & 4. Replacement of CVTs in line-3 is in progress. Each phase CVT supply was extended to Main 1 & Main -2 relays. Bus PT supply is extended for Sync.Check.
Time Delayed Auto Reclose (TDAR) scheme with Sync. Check, is being worked out and will be implemented for the four lines, on by one, before 31-03-2019.
Review meetinmg on 27.06.2019: No representative from the utility attended meeting and it is requested to submit NPCIL(MAPS) email dated 01.09.2020: Necessary approvals were taken for the scheme from station management for implementing the AR for all the 230kV lines. The AR will be implemented before 31-10-2020.
NPCIL (MAPS) email dated 02.11.2020: The Auto Reclose (AR) scheme is being tested at Relay Testing lab. The AR will be implemented, for all the 230kV lines of MAPS, before 31-12-2020.
NPCIL (MAPS) email dated December 2020: The Auto Reclose (AR) scheme is tested at Relay Testing lab. The test results are being reviewed by NPCIL, HQs. The AR will be implemented, for all the 230kV lines of MAPS, before 31-03-2021. This is for your information.
69/I/1 Complete outage of 400kV 25-10-2017 at 400 kV TPCIL-Nellore PS line-1 got tripped from TPCIL to configure DEF protection such that it remains in blocked condition as TPCIL Review Meeting on 21.12.2018: Pending TPCIL station 19:33 hrs TPCIL end during fault in 400kV Nellore-Nellore long as Distance Protection is active, and becomes active only when distance It was noted that no TPCIL representatives had come to attend the meeting PS line-2. Running units at TPCIL got tripped due protection does not pickup. to loss of evacuating line. 400kV Nellore PG - Review meetinmg on 27.06.2019: Nellore PS line-2 and 400kV TPCIL - Nellore PS No representative from the utility attended meeting and it is requested to submit line-1 were under shutdown. status regrading the recommendation at athe earliest.
Page 49 of 52 Annexure-C 78/II/2 Tripping of 400 kV Neyveli 01-08-2018 Triggering incident was failure of R-ph tension 1. NLCIL to furnish a report along with a suitable SLD on the tripping event NLCIL Review Meeting on 21.12.2018: Pending TS2Exp -Pugalur line at 11:56 hrs insulator string/ flashover in 400 kV Bus-1 at NLC explaining the observed discrepancies [DPR, Z1 operation, instantaneous NLCIL was asked to furnish the status of implementation of the recommendation TS2Exp end. Busbar protection had operated operation of OVR-II operation], and remedial action taken to attend the same. given at the earliest. resulting in tripping of all main breakers connected 2. NLCIL to configure DR’s & EL’s of all protection relays at their NLC TS- to 400kV Bus-1 at Neyveli TS2 Exp. In 400kV NLC IIExp station for all mandated protections & signals. Review meetinmg on 27.06.2019: TS2Exp - Pugalur line, fault was sensed in Zone-1, No representative from the utility attended meeting and it is requested to submit R-N at Pugalur end resulting in a single phase trip. status regrading the recommendation at athe earliest. Direct Trip was received at Pugalur end due to operation of over voltage Stg-2 at NLC TS2Exp.
79/II/8 Tripping of 400 kV NLC 10-09-2018 at Line tripped on B-N fault. Auto-reclose was not NLCIL to furnish a detailed report on tripping event explaining the observed NLCIL Review Meeting on 21.12.2018: Pending TS-2 (Exp) – Pugalur line 20:57 hrs attempted at Pugalur end due to DT receipt from discrepancies , and proper reasons for tripping of the line considering both the NLCIL was asked to furnish the status of implementation of the recommendation NLC TS2Exp end. At NLC TS2Exp end, V>2 trip Main-relays including remedial action taken w.r.t. healthiness/ replacement of given at the earliest. was observed in DR. Analog voltages recorded in Main protection relays on 400 kV NLC TS2Exp–Pugalur line. DR were observed to be less than that required for Review meetinmg on 27.06.2019: O/V Stage-II operation. it is requested to submit status regrading the recommendation at athe earliest.
80/II/17 Tripping of 400 kV Nellore 14-11-2018 at Y- ph to earth fault occurred in line due to snapping SGPL to examine the reasons for no-operation / failure of Auto-reclosure from SGPL Review meetinmg on 27.06.2019: Pending PS – SGPL line-1 20:20 hrs of GIS to Air bushing conductor at SGPL their end for the subject tripping, and furnish an action taken report detailing No representative from the utility attended meeting and it is requested to submit switchyard. The conductor got grounded such that remedial measures taken to PCSC forum. status regrading the recommendation at athe earliest. the fault was being fed by NPS bus and there was 80/III/6 Tripping of 400 kV 07-11-2018 at 400 kV Neyvelli TS2Exp - Pugalur tripped on NLCIL to furnish a detailed report on the reasons for A/R non-operation for the NLCIL Review meetinmg on 27.06.2019: Pending Neyvelli TS2 (Exp) - 05:50 Hrs B-phase to ground fault due to DPR, Z1 operation. subject tripping at their NLCTS2Exp station including remedial measures taken No representative from the utility attended meeting and it is requested to submit Pugalur line Auto-reclose was successful at Pugalur end and the to PCSC forum. status regrading the recommendation at athe earliest. line tripped at Neyveli TS2Exp end only. Auto- reclose was not attempted at Neyveli TS-2(Exp) end
83/III/1 Tripping of 220 kV 24-02-2019 at Line tripped on B-phase to earth fault. Auto-reclose It was noted that no representative of NTPC attended the meeting. NTPC (KYKLM) Review meeting on 27.06.2019: Pending Kayamkulam –Punnapura-2 03:05hrs was successful at Punnapura. A/r was not attempted NTPC (Kayamkulam) to furnish detailed report regarding failure of Auto- No representative from the utility attended meeting and it is requested to submit at Kayamkulam and there was pole discrepancy reclosure at Kayamkulam end for Kayamkulam –Punnapura line-2. status regrading the recommendation at athe earliest. operation resulting in tripping of R and Y pole of CB. NTPC mail dated 13.05.2019: Trip report for Tripping of 220 kV Kayamkulam –Punnapura-2 submitted , but for submitting detailed report for Auto-reclosure at Kayamkulam end not operating for Kayamkulam –Punnapura line-2 , half day shutdown of Kayamkulam –Punnapura line is required to check reason for failure . May please 83/III/2 Tripping of 220 kV 05-03-2019 at 220kV Kayamkulam-Punnapura -2 tripped on Zone- It was noted that no representative of NTPC attended the meeting. NTPC (KYKLM) Reviewapprove meetinghalf day outageon 27.06.2019: of Kayamkulam –Punnapura line and intimate us atleast Pending Kayamkulam –Punnapura-2 00:30hrs 1 distance protection due to R-N fault. Auto reclose NTPC (Kayamkulam) to furnish detailed report regarding failure of Auto- No representative from the utility attended meeting and it is requested to submit operated and successful at Punnapara end but didnot reclosure at Kayamkulam end for Kayamkulam –Punnapura line-2. status regrading the recommendation at athe earliest. operate at Kayamkulam end. NTPC mail dated 13.05.2019: Trip report for Tripping of 220 kV Kayamkulam –Punnapura-2 submitted , but for submitting detailed report for Auto-reclosure at Kayamkulam end not operating for Kayamkulam –Punnapura line-2 , half day shutdown of Kayamkulam –Punnapura line is required to check reason for failure . May please approve half day outage of Kayamkulam –Punnapura line and intimate us atleast one day in advance.
84/I/5 Complete outage of 400kV 05-06-2019at 18:51Triggering hr. incident was failure of Y-phase CT of GT-1 1.(Generator NLCIL to Transformer) check the healthiness at 400kV of NLC1EXP. R & B ph CTBus-1 of Unit-1Bus bar at protection NLC TS1(Exp) operated NLCIL resulting in the tripping of NLC1EXP U#1 and 400kV NLC1EXP-NLCIL mail Nagapattinam dated 09.07.2019: line Pending NLC1 and if found unhealthy replace the same alongwith replacement of Y-ph CT. CT AT TS2 Side Siemens 7SA52 & Micromho relay are used for distance protection. Expansion(NLC1EXP) replacement plan and timeframe shall be informed to SRPC. During the incident Micromho has sensed the CT blast as a Zone-1 fault and 2.NLCIL in coordination with PGCIL(SR-II) to resolve the time syncronisation tripped the feeder. Adt signal was send to TS1 Exp end. The relay will be tested issues in 230kV NLC TS1(Exp) – Nagapattinam line. during the next shut down. 3. NLCIL was also requested to investigate the reason of unwarranted DT sent to NLC TS1 (Exp) end from NLC TS2 end and resolve the same. NLCIL mail dated 11.01.2020: 3. Michro mho Relay Testing was carried out at TS2 end on 15/11/19 and found the relay was normal.Proposal has already been initiated to replace distance relays with line differential relays. It is also proposed to replace the PLCC panels at both ends. -- Completed 85/II/19 Tripping of 400kV JSW- 02-06-2019 at Line tripped due to OV St-1 protection operation at JSWEL is recommended to monitor the B-ph CVT of 400kV JSWEL-Guttur JSWEL Yet to be informed Pending Guttur line 18:17 hrs JSW end and DT was sent to Guttur end. At Guttur line (due to lower B-ph voltage compared to other two phases). The same shall end B ph voltage was observed to be lesser be replaced if the issue persists. comparing to R ph and Y ph(Vr-249kV, Vy-255kV and Vb-230kV).
Page 50 of 52 Annexure-C 85/II/21 Tripping of 400kV JSW - 05-06-2019 at Y-phase to earth fault occurred in 400kV Kaiga- 1. NPCIL (KGS) is recommended to identify the issue related to unsuccessful NPCIL (KGS) NPCIL mail dated 13.12.2019: Pending Guttur line and 400 kV 18:27 hrs Guttur line-2. A/r was successful at Guttur end. At A/R attempt of 400kV Kaiga – Guttur line and non-opening of R-pole CB. It is During the event Distance Protection Main-2 detected Y-ph fault and opened the Kaiga - Guttur line-2 Kaiga end A/r was not attempted and breakers got recommended to check the healthiness of all breakers including breaker timing. Y-ph pole and initiated A/R to process. tripped due to operation of Pole discrepancy (1.65 2. Time synchronization of DR and EL at Kaiga end shall be ensured. subsequent to that IN> started for B-ph. Actuation of IN> during the dead time Sec). 400kV JSW-Guttur line tripped on operation leads to A/R lockout. So pole discrepancy operated at kaiga end as per the of over-voltage at Guttur and direct trip was scheme. received at JSW. From DR of Guttur, it is observed DR and EL are already GPS synched at Kaiga end. that there was swell in R & Y phase voltage for few cycles NPCIL mail dated 18.03.2020: Event is forwarded for Designer review
85/IV/7 Tripping of 400kV 11-06-2019 at Line tripped due to Direct Trip receive at Ramadugu Singareni STPP is recommended to submit a detailed report regarding sending Singareni TPP Yet to be informed Pending Ramadugu-Singareni line 08:24 hrs end of DT from singareni end that resulted in tripping of 400kV Ramadugu- Singareni line.
86/III/2 Tripping of Kaiga-Gutur 22-07-2019 at Line tripped on B-phase to earth fault. Line did not NPCIL (KGS) to ensure time sync between DR and EL at Kaiga end. NPCIL NPCIL mail dated 13.12.2019: Pending line -2 17:47hr. auto-reclose. DR and EL are already GPS synched at Kaiga end. During the event Auto reclose was successful from KGS end. Due to existence of fault on B-phase, within 9 mili sec of closure, line CB-2B again tripped. As per information from Guttur end, insulator flash over took place at tower No:103.
87/III/4 Tripping of 400 kV Kaiga- 06-09-2019 at 4:33 Line tripped on Zone-1 distance protection operation due to R- NPCIL (KGS) to review A/R scheme at Kaiga GS. As per A/R logic, any phase to earth fault NLCIL (KGS) NPCIL mail dated 13.12.2019: Pending Narendra line-2 hr. phase to Y phase fault. At Kaiga end line auto-reclosed. detection should lead to opening of the faulted phase and reclosing after dead time. But during Distance protection of Main-2 detected R-ph fault and opened the R-ph pole, initiated A/R to dead time if any subsequent fault occurs it should block A/R and 3-ph trip should be extended. process.Subsequent to that Y-ph fault detected by Main-1 distance protection within 71 m.sec of Rph fault and opened the Yph-pole. Since Y-pole opened within the dead time and main-2 relay extended the close command to both the pole after laps of dead time as per scheme 88/III/7 Tripping of 400kV NLC TS-2 29-10-2019 at 16:43 Triggering incident was Y phase to Earth fault in the line. At NLCIL to submit a detailed report regarding the reason for failure of A/R in consultation with NLCIL Yet to be informed Pending Exp- Pugalur line hr. Pugalur end, fault was detected in Zone-1 and A/R operated OEM. successfully. At Neyveli TS-2 Exp end, fault was detected in Zone-1 and A/R not operated.
90/II/16 Tripping of 400kV Ramagundam - 07-03-2020 at 04:38 Triggering incident was Y N fault in the line. At Ramagundam NTPC (Rmgdm) to sort out the issue regarding maloperation of Main-1 relay and send a report NTPC(RMGDM) Yet to be informed Pending Malkaram Hr. end, fault was sensed in Zone-1, A/r operated and line tripped after replacement of the same. DR and EL at Ramagundam end for the subject line also need to be due to persistent fault. As per the report submitted at Malkaram time synchronized end, it was mentioned that line was in service; the same needs review. As per the report submitted by Ramagundam it was mentioned that, analog module of relay maloperates intermittently and the same needs review.
90/II/21 Tripping of 400kV Vallur – 19-Mar-2020 at Shutdown for 400kV Vallur- NCTPS line-1 was planned from i. NTECL-Vallur to ensure proper communication regarding remote end isolation before closing NTECL-Vallur Yet to be informed Pending NCTPS line-1 12:05 Hr. 09 hr. -1700 hr. on 19.03.2020. While closing NCTPS line 1 of earth switch in their switchyard to prevent recurrence of such faults in future. Earth switch at NTECL end, heavy voltage dip was experienced ii. NTECL-Vallur, in coordination with TANGEDCO, to restore communication channel between and all the three running units of Vallur tripped on Low the NTECL-Vallur and NCTPS and submit a report to SRPC regarding healthiness of the same. Forward Power Protection at 12:05 hr. Earth switch of the line was closed at Vallur end without opening of remote end breaker, which resulted in three phase to ground fault in 400kV Vallur - NCTPS line-1 at Vallur end. Gen Loss: 1893 MW. 90/IV /3 Tripping of 400kV Neyvelli 2 30-03-2020 at Triggering incident was Y-phase to ground fault in the line. NLCIL to submit a detailed report regarding A/R non-operation and sending of DT at Neyvelli 2 NLCIL Yet to be informed Pending (Exp) - Pugalur line 15:10Hr. Line tripped on Zone-1 distance protection.Auto reclose (Exp) end for the subject line. attempted but locked out due to persistent fault. At Pugalur end, DT was received resulting in 3phase trip.
DT sent from Neyvelli end needs review.
91/III/3 Tripping of 400kV 07-04-2020 • Triggering incident was B –N fault in the line. JSWEL to furnish detailed report regarding A/R non-operation at their end for the subject line and JSWEL Yet to be informed Pending JSW- at 16:10Hrs • At JSW end, line tripped on operation of Z1 distance the remedial measures taken for the same. Guttur line protection and A/r not operated. • At Guttur end, A/r operated successfully and line tripped due to subsequent fault during reclaim time.
91/III/5 Tripping of 400kV 09-04-2020 • Triggering incident was R phase to Earth fault in the line. NPCIL to submit report regarding unsuccessful A/R attempt at Kaiga end and Remedial measures NPCIL Yet to be informed Pending Kaiga- at 11:59 Hrs • At Guttur end, line tripped on operation of Zone-1 distance taken. Guttur line-1 protection and A/r not operated. • At Kaigaend,initially R pole got opened subsequently Y pole got open and it is suspected that line got tripped on operation of PD.
91/III/18 Tripping of 400kV 14-05-2020 • Triggering incident was B N fault in the line. NPCIL to submit report regarding unsuccessful A/R operation and remedial measures taken to NPCIL Yet to be informed Pending Kaiga- at 12:22Hrs • At Guttur end, Zone 2 carrier aided protection operated, A/r avoid the same. Guttur line-2 operated successfully and line was holding. • At Kaiga end, initially B pole breaker opened but subsequently R pole breaker also opened, A/r not operated and line tripped due to operation of PD
91/IV/1 Tripping of 400kV Ramagundam 18-04-2020 Line tripped only at Ramagundam end on DT receive. NTPC (Rmgdm) to submit a report regarding DC leakage in their switchyard and healthiness of NTPC (Rmgdm) Yet to be informed Pending Dichipally line at 13:10Hrs Suspected PLCC maloperation. PLCC channel.
16-05-2020 Line tripped only at Dichipalli end on DT Receive due to at 12:25Hrs suspected maloperation of PLCC during PLCC checking by TSTRANSCO at both the ends .
Page 51 of 52 Annexure-C 92/I/3 Complete outage of 220/33kV 29-06-2020 at 18:01 • Triggering incident was tripping of 220kV Pavagada - i. The SPDs were requested to maintain voltage and prevent injection of reactive power to grid, KSPDCL Yet to be informed Pending KSPDCL SS-5 (Thirumani) Hr. Thirumani line due to overvoltage at Thirumani end (only). Line especially during night. did not trip at Pavagada end. ii. SPDs requested to install suitable reactors, if they were not absorbing reactive power, as the • This resulted in complete outage of 220/33kV KSPDCL SS-5 issue would escalate in future with injection of more RE since the only connected feeder tripped.
92/II/15 Multiple Tripping in 400kV NLC 28-06-2020 at 15:28 • Triggering incident was failure of R-ph CT of 400kV NNTPP - i. NLCIL in consultation with TANTRANSCO to avoid overloading of ICTs at NLC complex. NLCIL Yet to be informed Pending TS-2 GS on 28-06-2020 at Hr Neyveli_TS-II Line at Neyveli_TS-II end. Line tripped on ii. NLCIL to ensure time synchronization of relays at Neyveli complex. 15:25Hr. operation of Differential protection at both the ends. • After the tripping of 400kV NNTPP -Neyveli_TS-II Line, 400kV/230kV,ICT - 1 and 2 at Neyveli_TS-II got over loaded and tripped on operation of overload protection. • Running units# 2 and 4 at Neyveli_TS-II end and U#1 at NNTPP also tripped during this event.
92/III/1 Tripping of 400kV JSW 01-06-2020 at 03:09 • Triggering incident was Y -N fault in the line. At JSW end, JSWEL to submit a report regrading non-operation of A/R at their end for the subject tripping JSWEL Yet to be informed Pending Toranagallu-Guttur line Hr. line tripped on operation of Z1 distance protection and A/r not incident. operated. • At Guttur end, A/r operated successfully and line tripped due to occurrence of subsequent fault, during reclaim time.
92/III/2 Tripping of 400kV Ramagundam 04-06-2020 at 08:26 • Triggering incident was Y-N fault in the line. At Ramagundam NTPC(Ramagundam) to submit a report regrading non-operation of A/R at their end for the NTPC(RMGDM) Yet to be informed Pending – Dichippalli line Hr. end, fault was sensed in Zone-1, initially Y pole opened, tripping. subsequently R and B poles also opened in 120ms.A/r not operated. • At Dichipalli end, fault was sensed in Zone-2, CAT protection operated and A/r operated. After A/r, line tripped on operation of Zone-2 due to non-receipt of carrier on persistent fault.
92/IV/3 Tripping of 400 kV 06-07-2020 at 12:17 • Line tripped only at Ramagundam end due to suspected NTPC (Ramagundam) to check the issue of PLCC maloperation at their end for the line. NTPC(RMGDM) Yet to be informed Pending Ramagundam– Dichippalli Line Hr. maloperation of PLCC. • Line was holding at Dichipalli end.
93/II/3 Tripping of 230 kV Bus-2 at 31-08-2020 at 05:56 • As reported, 230 kV TTPS –Kayathar line tripped on Y-phase NPCIL(KKNPP) to configure all zone pickups in Event logger of 230kV Kudankulam – TTPS NPCIL (KKNPP) Yet to be informed Pending TTPS station of TANGEDCO Hr. to ground fault. At the time of tripping, SF6 gas escaped line at Kudankulam end. Proper DRs shall also be made available for trippings. through the vent at the top of the breaker. • This led to operation of LBB protection and all elements connected to 230 kV Bus-2 at TTPS tripped. • Unit#2 at TTPS also tripped.
93/II/15 Multiple Tripping at 400/220 kV 02-08-2020 at 13:07 • Triggering incident was R-N fault in 220 kVRamagundam- i. NTPC- Ramagundam to submit a report after thoroughchecking of CVT circuit, to sort out the NTPC-Rmgdm Yet to be informed Pending Ramagundam GS Hr. Malayalapalli line-3. At the same time, 400 kVRamagundam - issue of faultyCVT secondary voltage measurement. Dichipalli line tripped only at Ramagundam end on OV Stage 2 ii. NTPC- Ramagundam in coordination with TSTRANSCO to perform PLCC end-to-end testing operation. for 400 kV Ramagundam – Dichipalli line.
94/I/11 Complete Outage of 230 kV 25-Nov-20 As per the information received, all connected lines tripped Bhavini to ensure that DR’s and EL’s of all protection relays are configured properly with all Bhavini Yet to be informed Pending BHAVINI 22:53 hrs only at Bhavini end due to Over voltage resulting in complete required protection (digital & analog) signals. loss of supply. Details are awaited.
94/II/34 Tripping of 400kV Bus-1 and Bus- 07-Dec-20 Triggering incident was Yph Bus Coupler CT failure at 400kV NLCIL to submit a detailed report regarding tripping of 400kV Buses at NLC TS-2 GS NLCIL Yet to be informed Pending 2 at 400kV/230kV NLC TS-2 18:59 hrs NLC TS-2. 400kV Bus-1 and Bus-2 BBP operated resulting in clarifying the following: Generating Station the tripping of all the connected elements. 230kV bus was intact i. Exact location of the fault, nature of fault during this event ii. Status of Bus coupler during fault iii. Whether BBP operated simultaneously for both buses, if not reason for the same and iv. Remedial measures taken for the tripping.
Page 52 of 52 Annexure-D
Pending Remedial Measures/ Actions taken for the Critical Tripping Incidents (as on 26.02.2021)
Sl.No ID ELE_NAME Outage_Date_Time Revival_Date_Time REASON SENDER / RECEIVER Remedial_measures REMEDY Reference FLAG RM by constituents
132kV SIDE TSTRANSCO/ 1 45690860 132KV-WADAPALLI-TANGEDA-1 03-01-2021/23:15:00 03-01-2021/23:50:00 To-be-discussed To-be-discussed FALSE PROBLEM APTRANSCO TSTRANSCO/ PGCIL(SR- 2 45690862 220KV-Warangal-NAGARAM-1 04-01-2021/03:55:00 04-01-2021/04:31:00 R-N FAULT To-be-discussed To-be-discussed FALSE 1) TSTRANSCO/ PGCIL(SR- 3 45690863 220KV-Warangal-NAGARAM-1 04-01-2021/04:36:00 04-01-2021/04:46:00 R-N FAULT To-be-discussed To-be-discussed FALSE 1) B PHASE TO 4 45690869 220KV-ASUPAKA-LOWER_SILERU-1 05-01-2021/11:52:00 05-01-2021/12:15:00 TSTRANSCO/ APGENCO To-be-discussed To-be-discussed FALSE GROUND
FLASH OVER IN 5 45690874 400KV-KOCHI-TRICHUR-1 06-01-2021/18:45:00 PGCIL(SR-2) To-be-discussed To-be-discussed FALSE GIS MODULE
TRIPPED ON 6 45690876 400KV/220KV HIRIYUR-ICT-1 07-01-2021/04:00:00 OVER FLUX PGCIL(SR-2) To-be-discussed To-be-discussed FALSE PROTECTION 7 45690878 400KV-KARAIKUDI-PUGALUR-1 07-01-2021/13:36:00 SWAPPING PGCIL(SR-2) To-be-discussed To-be-discussed FALSE
400KV-NELAMANGALA-TALGUPPA- B PHASE TO 8 45690884 08-01-2021/13:33:00 08-01-2021/15:41:00 KPTCL/ PGCIL(SR-2) To-be-discussed To-be-discussed FALSE 1 GROUND FAULT
TRIPPED ON Y 9 45690885 400KV-TALGUPPA-HASSAN-1 08-01-2021/06:48:00 08-01-2021/16:00:00 KPTCL/ PGCIL(SR-2) To-be-discussed To-be-discussed FALSE PHASE FAULT 10 45690887 220KV-AMBEWADI-XELDEM-1 08-01-2021/14:25:00 ABN FAULT KPTCL/ GED To-be-discussed To-be-discussed FALSE TRIPPED ON TANTRANSCO: During the incidence the feeder was 1. TANTRANSCO mail 11 45690888 230KV-BHAVANI-KANCHIPURAM-1 08-01-2021/23:58:00 DISTANCE TANTRANSCO To-be-discussed FALSE radially fed from Bhavini dated 21.01.2021. PROTECTION TSTRANSCO/ 12 45690892 132KV-KUSMANTHI-CHIKALLU-1 09-01-2021/11:26:00 B-N FAULT To-be-discussed To-be-discussed FALSE APTRANSCO APTRANSCO: Line patrolling not done. After taking APTRANSCO/ 1. APTRANSCO mail 13 45690896 400KV-SATTENPALLY-PODILI-1 10-01-2021/14:31:00 YB FAULT permission from SLDC, the line was charged and stood FALSE TSTRANSCO dated 05.02.2021 ok.
220KV-SRISAILAM_RIGHT_BANK- 14 45690899 12-01-2021/10:59:00 12-01-2021/11:50:00 R PHASE FAULT APGENCO/ TSTRANSCO To-be-discussed To-be-discussed FALSE NAGARJU ..
TSGENCO: On 12.01.2021 at 12:49 Hrs 400KV Julurupadu Manuguru-2 Feeder was tripped on B Phase to ground fault at a distance of 61.34Kms from 400KV-JULURUPADU-MANUGURU- 1. TSGENCO email 15 45690900 12-01-2021/13:23:00 12-01-2021/18:33:00 R-N FAULT TSGENCO/ TSTRANSCO Manuguru end, After getting clearance from SLDC, line To-be-discussed FALSE 1 dated 04.02.2021 charged at 13.29 Hrs. on 12-01-2021.Line stood ok.
Status of A/R?
TSGENCO: On 12.01.2021 at 13:23 Hrs 400KV Julurupadu Manuguru Feeder was tripped on R Phase to ground fault at a distance of 40.1 Kms from Manuguru 400KV-JULURUPADU-MANUGURU- 1. TSGENCO email 16 45690901 12-01-2021/12:49:00 12-01-2021/13:29:00 B-N FAULT TSGENCO/ TSTRANSCO end. After getting clearance from SLDC, line charged at To-be-discussed FALSE 2 dated 04.02.2021 18:34 Hrs. on 12-01-2021.Line stood ok.
Status of A/R?
RELAY 17 45690902 400KV-HOODY-DEVANAHALLI-1 13-01-2021/02:23:00 KPTCL To-be-discussed To-be-discussed FALSE MALOPERATION
Tripped on bus bar 18 45690903 230KV/6.6KV Neyveli TS II-ST-2 13-01-2021/09:50:00 13-01-2021/17:42:00 NLCIL To-be-discussed To-be-discussed FALSE protection BUS BAR 19 45690905 400KV/230KV NEYVELI_TS_II-ICT-1 13-01-2021/14:50:00 13-01-2021/15:17:00 PROTECTION NLCIL To-be-discussed To-be-discussed FALSE OPERATED
Page 1 of 6 Annexure-D
BUS BAR 20 45690906 400KV/230KV NEYVELI_TS_II-ICT-2 13-01-2021/09:50:00 13-01-2021/12:43:00 PROTECTION NLCIL To-be-discussed To-be-discussed FALSE OPERATED BUS BAR 21 45690907 400KV/230KV NEYVELI_TS_II-ICT-2 13-01-2021/14:50:00 13-01-2021/15:17:00 PROTECTION NLCIL To-be-discussed To-be-discussed FALSE OPERATED BUS BAR 22 45690909 230KV/6.6KV Neyveli TS II-ST-4 13-01-2021/14:50:00 PROTECTION NLCIL To-be-discussed To-be-discussed FALSE OPERATED 220KV-CHILLAKALLU- 23 45690911 13-01-2021/15:04:00 13-01-2021/15:29:00 R-G FAULT NLCIL To-be-discussed To-be-discussed FALSE PULICHINTALA-1 BUS BAR 230KV-NEYVELI_TS_II-NLC MINES- 24 45690912 13-01-2021/14:50:00 13-01-2021/15:17:00 PROTECTION NLCIL To-be-discussed To-be-discussed FALSE 3 OPERATED BUS BAR 230KV-NEYVELI_TS_II-NLC MINES- 25 45690913 13-01-2021/14:50:00 13-01-2021/15:17:00 PROTECTION NLCIL To-be-discussed To-be-discussed FALSE 4 OPERATED
Bus bar protection 26 45690918 230KV-NEYVELI_TS_II-STCMS 13-01-2021/14:50:00 13-01-2021/18:41:00 NLCIL/STCMS To-be-discussed To-be-discussed FALSE operated
BUSBAR 230KV-NEYVELI_TS_II- PROTECTION TANTRANSCO: During the incident feeder was holding 1. TANTRANSCO mail 27 45690919 13-01-2021/14:50:00 13-01-2021/18:38:00 NLCIL/ TANTRANSCO To-be-discussed FALSE ULUNDURPET-1 OPERATED AT at ULUNDURPET end. dated 23.02.2021 230 kV SIDE Tripped on bus bar 28 45690920 230KV-NLC-TNEB-NEYVELI_TS_II-2 13-01-2021/09:50:00 13-01-2021/13:46:00 NLCIL To-be-discussed To-be-discussed FALSE protection BUSBAR PROTECTION 29 45690921 230KV-NNTPP-NEYVELI_TS1-1 13-01-2021/14:50:00 13-01-2021/15:17:00 NLCIL To-be-discussed To-be-discussed FALSE OPERATED AT 230 kV SIDE Tripped on bus bar 30 45690922 230KV-NNTPP-NEYVELI_TS_II-2 13-01-2021/09:50:00 13-01-2021/18:59:00 NLCIL To-be-discussed To-be-discussed FALSE protection BUS BAR TANTRANSCO: During the incident feeder was holding 1. TANTRANSCO mail 31 45690923 230KV-NNTPP-NLC-TNEB-2 13-01-2021/14:50:00 13-01-2021/18:30:00 PROTECTION NLCIL/ TANTRANSCO To-be-discussed FALSE at TNEB end. dated 23.02.2021 OPERATED TANTRANSCO: For a B PHASE to ground , B phase got tripped & AR sucessful at KADALANGUDI end. 230KV-NEYVELI_TS_II- 1. TANTRANSCO mail 32 45690924 13-01-2021/06:37:00 B-N FAULT NLCIL/ TANTRANSCO Remedial action: NIL To-be-discussed FALSE KADALANGUDI dated 23.02.2021 NLCIL to reply 400KV-GAZUWAKA-VEMAGIRI_PG- 33 45690927 15-01-2021/15:40:00 15-01-2021/16:26:00 B-N FAULT PGCIL-SR-1 To-be-discussed To-be-discussed FALSE 1 UT pressure relief 1. APTRANSCO mail 34 45690929 400KV/11KV IL&FS-GT-1 16-01-2021/08:06:00 16-01-2021/16:55:00 limit switch ILFS/ APTRANSCO To-be-discussed To-be-discussed FALSE dated 05.02.2021 malfunction
220KV-SRISAILAM_RIGHT_BANK- 35 45690930 16-01-2021/12:58:00 16-01-2021/13:36:00 R-N FAULT APGENCO/ TSTRANSCO To-be-discussed To-be-discussed FALSE NAGARJU ..
KSEBL: -- On 17-01-2021 at 14:50hrs, bus differentialprotection ALONG WITH operated with R- phase indication, and LBB initiated THE from 2IDKL #2for R- phase. All generators, feeders and 1. KSEBL mail dated CONDUCTOR 50MVA, 220/66 kV transformerconnected to both the 23.02.2021. 220KV-UDUMALPET_TN-IDDUKKI- 36 45690931 17-01-2021/14:50:00 17-01-2021/16:08:00 SNAPPING OF TANTRANSCO/ KSEBL bus bars tripped. To-be-discussed FALSE 1 220KV IDUKKI 2. TANTRANSCO mail KALAMASSERY RM taken? dated 23.02.2021 #2 FEEDER TANTRANSCO: During the incident feeder was holding at Udumelpet end. ZONE 1 37 45690934 220KV-AMBEWADI-XELDEM-1 19-01-2021/13:46:00 KPTCL/ GED To-be-discussed To-be-discussed FALSE OPERATED Differential relay 38 45690936 400KV/230KV ARASUR-ICT-3 20-01-2021/06:03:00 20-01-2021/23:27:00 PGCIL-SR-2 To-be-discussed To-be-discussed FALSE operated
Page 2 of 6 Annexure-D
MAL OPERATION 39 45690937 400KV/220KV SURYAPET-ICT-2 20-01-2021/22:25:00 21-01-2021/04:48:00 TSTRANSCO To-be-discussed To-be-discussed FALSE TRIPPED ON LV SIDE TRIPPED ON 40 45690938 400KV-VTPS_IV-SURYAPET-1 20-01-2021/20:57:00 20-01-2021/23:24:00 RELAY MAL TSTRANSCO To-be-discussed To-be-discussed FALSE OPERATION TRIPPED ON 41 45690940 400KV-SURYAPET-JULURUPADU-2 20-01-2021/20:57:00 20-01-2021/23:15:00 RELAY MAL TSTRANSCO To-be-discussed To-be-discussed FALSE OPERATION Triiped on R-B 42 45690941 765KV-SRIKAKULAM-ANGUL-1 20-01-2021/17:36:00 20-01-2021/19:38:00 PGCIL-SR-1 To-be-discussed To-be-discussed FALSE Fault TRIPPED ON TSTRANSCO/ 43 45690942 400KV-SURYAPET-KV_KOTA-1 20-01-2021/20:57:00 RELAY MAL To-be-discussed To-be-discussed FALSE APTRANSCO OPERATION TRIPPED ON 44 45690943 400KV-VTPS_IV-SURYAPET-2 20-01-2021/20:57:00 RELAY MAL APGENCO/ TSTARNSCO To-be-discussed To-be-discussed FALSE OPERATION TRIPPED ON 45 45690945 400KV-MALKARAM-SURYAPET-1 20-01-2021/20:57:00 RELAY MAL TSTRANSCO To-be-discussed To-be-discussed FALSE OPERATION
Y-Phase jumper of 220 KV Boyareddy pally feeder fallen 46 45690946 400KV/220KV GOOTY-ICT-1 21-01-2021/14:24:00 21-01-2021/18:06:00 on Bus-I leading to PGCIL-SR-1 To-be-discussed To-be-discussed FALSE tripping of 3 NOs. ICTs feedres and all 220 kv feeders
Y-Phase jumper of 220 KV Boyareddy pally feeder fallen 47 45690947 400KV/220KV GOOTY-ICT-2 21-01-2021/14:24:00 21-01-2021/16:25:00 on Bus-I leading to PGCIL-SR-1 To-be-discussed To-be-discussed FALSE tripping of 3 NOs. ICTs feedres and all 220 kv feeders
Y-Phase jumper of 220 KV Boyareddy pally feeder fallen 48 45690948 400KV/220KV GOOTY-ICT-3 21-01-2021/14:24:00 21-01-2021/16:05:00 on Bus-I leading to PGCIL-SR-1 To-be-discussed To-be-discussed FALSE tripping of 3 NOs. ICTs feedres and all 220 kv feeders
TRIP COIL 49 45690949 400KV-KAIGA-GUTTUR-2 21-01-2021/20:30:00 NPCIL(KGS)/ KPTCL To-be-discussed To-be-discussed FALSE FAULTY 400KV-SRISAILAM_LEFT_BANK- DT Received at 50 45690950 22-01-2021/15:58:00 22-01-2021/16:34:00 TSGENCO/ TSTRANSCO To-be-discussed To-be-discussed FALSE DINDI-1 SSLM End 400KV-RAMAGUNDAM-NTPC- suspected relay mal NTPC(RMGDM)/ 51 45690952 24-01-2021/19:54:00 To-be-discussed To-be-discussed FALSE TELANGANA STPP-2 operartion TSGENCO NORTH BUS 52 45690953 400KV/220KV HOODY-ICT-2 25-01-2021/00:42:00 25-01-2021/03:13:00 KPTCL To-be-discussed To-be-discussed FALSE FLASH OVER NORTH BUS 53 45690954 400KV-HOODY-DEVANAHALLI-1 25-01-2021/00:42:00 KPTCL To-be-discussed To-be-discussed FALSE FLASH OVER NPCIL(KKNPP)/ 54 45690958 230KV-KUDANKULAM-TTPS 27-01-2021/13:19:00 27-01-2021/14:08:00 B-N FAULT To-be-discussed To-be-discussed FALSE TANGEDCO H/T ON 55 45690960 400KV-UPCL-HASSAN-1 29-01-2021/00:07:00 VOLTAGE UPCL/ PGCIL-SR-2 To-be-discussed To-be-discussed FALSE REGULATION Busbar protection 56 45690961 400KV/220KV DICHPALLY-ICT-2 29-01-2021/12:07:00 29-01-2021/13:18:00 operated at 220kV TSTRANSCO To-be-discussed To-be-discussed FALSE Side
Page 3 of 6 Annexure-D
220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at 220KV-AMBALAMUGAL- opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 57 45690962 29-01-2021/11:42:00 29-01-2021/12:00:00 KSEBL To-be-discussed FALSE SABARIGIRI-1 EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 58 45690963 220KV-EDAMON-EDAPPON-1 29-01-2021/11:42:00 29-01-2021/12:30:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 59 45690964 220KV-EDAMON-POTHENCODE-1 29-01-2021/11:42:00 29-01-2021/12:02:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 60 45690965 220KV-EDAMON-POTHENCODE-2 29-01-2021/11:42:00 29-01-2021/11:56:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 61 45690966 220KV-EDAMON-SABARIGIRI-1 29-01-2021/11:42:00 29-01-2021/12:29:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 62 45690967 220KV-EDAMON-SABARIGIRI-2 29-01-2021/11:42:00 29-01-2021/12:22:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 63 45690968 220KV-EDAMON-SABARIGIRI-3 29-01-2021/11:42:00 29-01-2021/12:55:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 64 45690969 220KV-SABARIGIRI-PALLOM-1 29-01-2021/11:42:00 29-01-2021/12:53:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house.
due to an accidental 65 45690970 220KV-THENI-MOOZIYAR-1 29-01-2021/11:42:00 29-01-2021/12:42:00 TANTRANSCO To-be-discussed To-be-discussed FALSE equipmental PET testing on one bus.
220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 66 45690971 220KV-EDAMON-KUNDARA-1 29-01-2021/11:42:00 29-01-2021/12:33:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 67 45690972 220KV-TIRUNELVELI-EDAMON-1 29-01-2021/11:42:00 29-01-2021/12:36:00 PGCIL-SR-2 To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house. 220kV bus bar KSEBL: On 29-01-2021 at 11:43Hrs 220kV feeders at opearted at 220kVSubstation, Edamon got tripped due to bus fault. 1. KSEBL mail dated 68 45690973 220KV-TIRUNELVELI-EDAMON-2 29-01-2021/11:42:00 29-01-2021/12:42:00 KSEBL To-be-discussed FALSE EDAMON during This resulted in the totaloutage of 220kV Substation, 22.02.2021 relay testing Edamon and Sabarigiri power house.
69 45690974 400KV-GAJWEL-CHANDALAPUR-2 30-01-2021/07:16:00 30-01-2021/08:42:00 distance protection TSTRANSCO To-be-discussed To-be-discussed FALSE
tie CB LBB has mal-operated at 70 45690975 765KV-NIZAMABAD-WARDHA-1 30-01-2021/13:00:00 30-01-2021/14:00:00 wardha end ,DT PGCIL-SR-1/ WR To-be-discussed To-be-discussed FALSE received at nizamabad end H/T ON 71 45690976 400KV/220KV ASUPAKA-ICT-2 31-01-2021/17:54:00 VOLTAGE TSTRANSCO To-be-discussed To-be-discussed FALSE REGULATION 220KV-KOTHAGUDEM_TPS- TRIPPED ON Y-N 1. TSGENCO email 72 45690977 31-01-2021/15:04:00 31-01-2021/15:34:00 TSGENCO/ APTRANSCO To-be-discussed To-be-discussed FALSE NUNNA_AP-1 FAULT dated 04.02.2021 H/T ON 765KV-CHILAKALURIPETA- 73 45690978 31-01-2021/18:11:00 VOLTAGE PGCIL-SR-1 To-be-discussed To-be-discussed FALSE VEMAGIRI_PG-2 REGULATION
Page 4 of 6 Annexure-D
R PHASE JUMPER CUT 74 45690979 400KV-NCTPS_STAGE_II-VALLUR-1 01-02-2021/09:18 01-02-2021/19:35 NEAR TOWER TANGEDCO/ NTECL To-be-discussed To-be-discussed FALSE NO 3 OF VALLUR TSTRANSCO/ PGCIL(SR- 75 45691060 220KV-Warangal-NAGARAM-1 02-02-2021/21:45:00 02-02-2021/23:35:00 R-N FAULT To-be-discussed To-be-discussed FALSE 1) TRIPPED ON 76 45691061 400KV-SURYAPET-JULURUPADU-1 02-02-2021/14:07:00 02-02-2021/17:01:00 DISTANCE TSTRANSCO To-be-discussed To-be-discussed FALSE PROTECTION 400KV-GHANAPUR-RAMAGUNDAM- TRIPPED DUE PGCIL-SR-1/ NTPC- 77 45691062 03-02-2021/01:24:00 03-02-2021/02:31:00 To-be-discussed To-be-discussed FALSE 4 TO R-N FAULT RMDGM 78 45691063 400KV/220KV GUTTUR-ICT-1 03-02-2021/13:15:00 03-02-2021/13:28:00 bus bar operated KPTCL To-be-discussed To-be-discussed FALSE 79 45691064 400KV/220KV GUTTUR-ICT-2 03-02-2021/13:15:00 03-02-2021/13:29:00 bus bar operated KPTCL To-be-discussed To-be-discussed FALSE TSTRANSCO/ 80 45691065 132KV-WADAPALLI-TANGEDA-1 03-02-2021/11:03:00 03-02-2021/11:33:00 B-N FAULT To-be-discussed To-be-discussed FALSE APTRANSCO
81 45691066 220KV-ASUPAKA-LOWER_SILERU-1 03-02-2021/15:56:00 03-02-2021/16:40:00 R-N FAULT TSTRANSCO/ APGENCO To-be-discussed To-be-discussed FALSE
H/T DUE TO SF6 220KV-SULURPET- APTRANSCO/ 82 45691067 04-02-2021/13:08:00 04-02-2021/17:32:00 GAS PRESSURE To-be-discussed To-be-discussed FALSE GUMMIDIPOONDI-1 TANTRANSCO LOW
SINGLE PHASE 83 45691068 400KV-MEHBOOBNAGAR-RTPS-1 04-02-2021/06:43:00 04-02-2021/07:28:00 PGCIL-SR-1 To-be-discussed To-be-discussed FALSE FAULT B-Ph LA Flash 132KV-KUZHITHURAI-PARASSALA- 84 45691069 04-02-2021/21:02:00 Over at Parsala KSEBL/ TANTRANSCO To-be-discussed To-be-discussed FALSE 1 End LV SIDE Y- 85 45691070 400KV/220KV ASUPAKA-ICT-2 05-02-2021/12:35:00 PHASE LBB TSTRANSCO To-be-discussed To-be-discussed FALSE INITIATED 220KV-KOTHAGUDEM_TPS- 86 45691071 05-02-2021/21:08:00 05-02-2021/21:25:00 B-N FAULT TSGENCO/ APTRANSCO To-be-discussed To-be-discussed FALSE NUNNA_AP-1 220KV-SULURPET- APTRANSCO/ 87 45691072 05-02-2021/12:37:00 05-02-2021/17:08:00 Y-B-N Fault To-be-discussed To-be-discussed FALSE GUMMIDIPOONDI-1 TANTRANSCO TRIPPED ON Y-N APTRANSCO/ 88 45691073 400KV-KALPAKKA-ASUPAKA-1 05-02-2021/13:00:00 To-be-discussed To-be-discussed FALSE FAULT TSTRANSCO 220KV-NARENDRA_PG- 89 45691074 06-02-2021/14:40:00 07-02-2021/00:32:00 B-N FAULT PGCIL-SR-1/ KPTCL To-be-discussed To-be-discussed FALSE MAHALINGAPURA-1 220KV-KOTHAGUDEM_TPS- 90 45691076 07-02-2021/12:55:00 07-02-2021/13:06:00 B PHASE FAULT TSGENCO/ APTRANSCO To-be-discussed To-be-discussed FALSE NUNNA_AP-1 Tripped on B-N 220KV-KOTHAGUDEM_TPS- 91 45691077 07-02-2021/13:40:00 07-02-2021/14:13:00 FAULT at KTPS TSGENCO/ APTRANSCO To-be-discussed To-be-discussed FALSE NUNNA_AP-1 end 400KV-KRISHNAPATNAM- 92 45691078 07-02-2021/21:13:00 R-N FAULT APGENCO/ APTRANSCO To-be-discussed To-be-discussed FALSE RACHAGUNNERI-1 20kV Bus-2 LBB operated (220kV 93 45691082 400KV/220KV GAJWEL-ICT-1 08-02-2021/06:25:00 31-01-2021/10:57:00 TSTRANSCO To-be-discussed To-be-discussed FALSE Medchal feeder CB limb failure) DISTANCE 94 45691083 400KV-KAIGA-GUTTUR-2 08-02-2021/13:26:00 NPCIL(KGS)/ KPTCL To-be-discussed To-be-discussed FALSE PROTECTION 95 45691085 400KV/220KV NIRMAL-ICT-2 09-02-2021/00:57:00 09-02-2021/03:33:00 maloperation TSTRANSCO To-be-discussed To-be-discussed FALSE 230KV-KALVENDAPATTU- POLE 96 45691086 09-02-2021/14:00:00 09-02-2021/15:52:00 TANTRANSCO To-be-discussed To-be-discussed FALSE THARAMANI DESCRIPENCY 97 45691088 400KV-UPCL-HASSAN-1 11-02-2021/17:43:00 R-N FAULT UPCL/ PGCIL-SR-2 To-be-discussed To-be-discussed FALSE LA FLASH OVER 98 45691091 400KV/230KV ALAMATHY-ICT-4 13-02-2021/23:21:00 TANTRANSCO To-be-discussed To-be-discussed FALSE HV SIDE
99 45691092 230KV-PUDUCHERRY-BAHOOR-1 14-02-2021/11:01:00 14-02-2021/11:26:00 B PHASE FAULT PED To-be-discussed To-be-discussed FALSE
B PHASE TO PGCIL-SR2/ 100 45691093 400KV-KARAIKUDI-KAMUDHI-1 14-02-2021/11:38:00 14-02-2021/21:10:00 To-be-discussed To-be-discussed FALSE GROUND TANTRANSCO tripped due to 101 45691095 400KV-BPS-JAGALUR-2 15-02-2021/17:28:00 15-02-2021/18:26:00 master trip relay KPTCL To-be-discussed To-be-discussed FALSE operated
Page 5 of 6 Annexure-D
400KV-KALVENDAPATTU-VALLUR- DISTANCE 102 45691096 16-02-2021/14:30:00 16-02-2021/16:06:00 TANTRANSCO/ NTECL To-be-discussed To-be-discussed FALSE 1 PROTECTION Heavy glow hand 103 45691097 400KV-KARAMADAI-ARASUR-1 16-02-2021/12:25:00 16-02-2021/18:13:00 tripped without TANTRANSCO To-be-discussed To-be-discussed FALSE code 400KV-JULURUPADU-MANUGURU- TRIPPED ON R-N 104 45691098 16-02-2021/12:29:00 16-02-2021/16:32:00 TANTRANSCO To-be-discussed To-be-discussed FALSE 1 FAULLT BUSBAR PROTECTION 105 45691099 400KV/220KV GUTTUR-ICT-1 18-02-2021/11:10:00 18-02-2021/11:32:00 OPERATED AT TANTRANSCO To-be-discussed To-be-discussed FALSE GUTTUR 220KV SIDE BUSBAR PROTECTION 106 45691100 400KV/220KV GUTTUR-ICT-2 18-02-2021/11:10:00 18-02-2021/11:52:00 OPERATED AT TANTRANSCO To-be-discussed To-be-discussed FALSE GUTTUR 220KV SIDE DT RECEIVED 107 45691101 400KV-KAIGA-GUTTUR-1 18-02-2021/11:10:00 18-02-2021/11:33:00 TANTRANSCO To-be-discussed To-be-discussed FALSE AT KAIGA END Differential relay 108 45691102 400KV/230KV ALAMATHY-ICT-4 19-02-2021/12:09:00 19-02-2021/18:37:00 TANTRANSCO To-be-discussed To-be-discussed FALSE operated
TRIPPED ALONG 109 45691103 400KV/230KV ALAMATHY-ICT-3 19-02-2021/23:49:00 20-02-2021/04:14:00 TANTRANSCO To-be-discussed To-be-discussed FALSE WITH LINE
132KV-ASWAROAPET- TRIPPED ON APTRANSCO/ 110 45691105 21-02-2021/11:06:00 21-02-2021/12:43:00 To-be-discussed To-be-discussed FALSE KAMAVARAPU_KOTA .. OVER LOAD TSTRANSCO 400KV-KRISHNAPATNAM- 111 45691106 23-02-2021/02:02:00 R-N FAULT APGENCO/ APTRANSCO To-be-discussed To-be-discussed FALSE RACHAGUNNERI-1
220 kV BUS BAR 112 45691107 220KV-KAIGA-KADRA-1 23-02-2021/13:30:00 23-02-2021/17:18:00 KPCL/ NPCIL(KGS) To-be-discussed To-be-discussed FALSE OPERATED
TRIPPED ON B-N 113 45691108 220KV-AMBEWADI-XELDEM-1 24-02-2021/10:46:00 24-02-2021/19:22:00 KPTCL/ GED To-be-discussed To-be-discussed FALSE FAULT 220KV-KAYAMKULAM-PUNNAPRA- 114 45691109 24-02-2021/17:19:00 24-02-2021/17:47:00 DT RECEIVED NTPC-KYMKLM/ KSEBL To-be-discussed To-be-discussed FALSE 1 TRIPPED ON B-N 115 45691110 220KV-AMBEWADI-XELDEM-1 25-02-2021/11:29:00 25-02-2021/19:15:00 KPTCL/ GED To-be-discussed To-be-discussed FALSE FAULT 220KV-UDUMALPET_TN-IDDUKKI- 116 45691111 25-02-2021/18:33:00 25-02-2021/19:25:00 R PHASE FAULT TANTRANSCO/ KSEBL To-be-discussed To-be-discussed FALSE 1
Directional earth 117 45691112 400KV-BIDADI-TUMKUR-1 25-02-2021/14:14:00 25-02-2021/15:19:00 PGCIL-SR-2 To-be-discussed To-be-discussed FALSE fault relay operated
118 45691113 400KV-BIDADI-NELAMANGALA-1 25-02-2021/14:14:00 25-02-2021/14:39:00 R-N FAULT PGCIL-SR-2/ KPTCL To-be-discussed To-be-discussed FALSE
119 45691114 400KV-BIDADI-NELAMANGALA-2 25-02-2021/14:14:00 25-02-2021/14:40:00 R-N FAULT PGCIL-SR-2/ KPTCL To-be-discussed To-be-discussed FALSE
400KV-MAHESHWARAM_TG-DINDI- B PHASE TO 120 45691115 25-02-2021/13:15:00 25-02-2021/18:27:00 TSTRANSCO To-be-discussed To-be-discussed FALSE 1 GROUND FAULT
121 45691116 220KV-AMBEWADI-XELDEM-1 25-02-2021/22:49:00 B PHASE FAULT KPTCL/ GED To-be-discussed To-be-discussed FALSE
400KV-KRISHNAPATNAM- 122 45691117 25-02-2021/18:56:00 R-Y FAULT APGENCO/ APTRANSCO To-be-discussed To-be-discussed FALSE RACHAGUNNERI-1 400KV-TUTICORIN_PS- TRIPPED ON Y-N 123 45691118 25-02-2021/12:37:00 PGCIL-Sr-2 To-be-discussed To-be-discussed FALSE DHARMAPURI-1 FAULT
124 45691119 220KV-Warangal-NAGARAM-2 26-02-2021/02:32:00 26-02-2021/03:06:00 C PHASE FAULT TSTRANSCO To-be-discussed To-be-discussed FALSE
Page 6 of 6 Annexure-E
Page 1 of 2 Annexure-E
Page 2 of 2 Annexure-F
94th PCSC meeting
SRLDC, POSOCO 29th January 2021
1 Page 1 of 153 Annexure-F
Details of Grid Disturbances
2 Page 2 of 153 Annexure-F
3 Page 3 of 153 Annexure-F
4 Page 4 of 153 Annexure-F
5 Page 5 of 153 Annexure-F
6 Page 6 of 153 Annexure-F 94.I.1. Complete Outage of 220kV Sabarigiri GS of KSEB at 18:07 Hrs on 01-10-2020
Weather Double bus Normal with bus coupler
Load Loss- 16 MW
Generation U#1, #2, #3 Loss- 220 MW and #5 in service
• Triggering incident was R phase CT failure of 220kV Sabarigiri Edamon line-2 at Sabarigiri end.
• Fault was between CT and breaker.
7 Page 7 of 153 Annexure-F
PRECEDENT BUS CONFIGURATION AND SERVICE CONDITION AT SABARIGIRI HEP ON 10/01/2020 AT 00:30 HRS
8 Page 8 of 153 Annexure-F • Bus-1 BBP operated resulting in the tripping of all the elements. However, fault current was observed to be persistent for 200ms at Sabarigiri end and the same needs review. • At Edamon end, line tripped on operation of Zone-2 distance protection and hence delayed fault clearance of 350ms was observed. • Other elements connected to Bus-2 at 220kV Sabarigiri were hand tripped. PMU Plots
Delayed fault clearance of 400ms
9 Page 9 of 153 Annexure-F Points for Review:
(1). Breaker statuses were not available in DRs furnished making it difficult to analyse. (2). 220kV/66kV 50 MVA Transformer Trip DR in BB Panel shall be furnished. (3). Non-opening of R pole CB of 220kV Sabarigiri Edamon line-2 at Sabarigiri end. (4). Main-1 and Main-2 line DR of 220kV Sabarigiri Edamon line-2 at Sabarigiri end (only one main DR was furnished). (5). Ambiguity in fault location and sensing of fault by 220kV Sabarigiri Edamon line-2 at Sabarigiri end. (6). Tripping of U#2 (connected at Bus-2) during BBP operation of Bus-1. (7). Reason for hand tripping of healthy lines and running units.
10 Page 10 of 153 DR analysis: Annexure-F
11 Page 11 of 153 Annexure-F
12 Page 12 of 153 Annexure-F
13 Page 13 of 153 Annexure-F SCADA Plot:
Remedial Actions Furnished:
The end zone protection was not configured in the numerical bus bar protection. The technical possibility for providing end zone protection is to be explored. This will be carried out by 30-ll-2020. Stage2 LBB period is presently 250ms which is to be reduced to 20Oms.This will be carried out by 30-ll-2020. Instruction has been conveyed to the operator to avoid unnecessary switching off healthy bays unless it is dangerous to human beings. Faulty R phase CT of SBEM#2 feeder was replaced with a new one. 14 Page 14 of 153 94.I.2. Complete outage of 220/66kV KSPDCL SS-6 Annexure-F (Pavagada) of KSPDCL at 14:02 Hrs on 06-10-2020
Weather Double Bus Normal with BC
Generation Loss-179MW
• Triggering Incident: R phase to Earth fault in 66kV Feeder no-10 of KSPDCL SS- 6. Feeder got tripped on operation of Earth fault overcurrent protection. • At the same time, 220kV Pavagada - Thirumani line-2 tripped only at Pavagada end on operation of Zone-1 distance protection. • This resulted in complete outage of 220/66kV KSPDCL SS-6 since the only connected feeder tripped.
15 Page 15 of 153 Annexure-F PMU Plot No Delayed fault clearance
DR Analysis
SRLDC e-Mail to SR-2
16 Page 16 of 153 Annexure-F Remedial Actions Furnished:
1. As per the OEM suggestion, additional PSL logic was implemented to block the distance protection, when channel fail alarm not there. The same is intimated to KSPDCL end also. 2. The relay settings for the line were issued by KSPDCL. Implemented settings were verified at Pavagada end and found matching with the recommended settings. 3. As Overhead line is followed by cable, over reach in Z1 might have caused due to cable capacitance effect or due to non-homogeneity of renewable energy sources. 4. M/s GE (OEM of the relay) also recommended to review the zone settings considering the cable capacitance effect. 5. The same is intimated to M/s KSPDCL for further review of relay settings.
Main-1 Relay – Micom P543 Main-2 Relay – Siemens 7SD522 1. From the DR of Main-1 P543, during the pre-fault condition, Local and Remote currents were found balanced and no differential current was observed. 2. But during fault condition, differential current in the order of 200A observed. 17 Page 17 of 153 94.I.3. Complete Outage of 220kV Nandhihal SwitchingAnnexure-F Station of Siemens Gamesha, 220kV Bijapur and 220kV Indi SS of KPTCL at 22:25 Hrs on 17-10-2020
Weather
Normal
Load Loss- 52MW
Generation Loss-68MW
• Triggering Incident: Y phase metering CT failure of 220kV Nandihal Switching SS -GM Navara line-1 at Nandihal Switching SS end. • Failed CT parts fell on Bus-1 and created RY fault at 220kV Nandhihal Switching SS. Hence Bus-1 BBP operated resulting in the tripping of all the elements at 220kV Nandhihal Switching SS. 18 Page 18 of 153 PMU Plots No Delayed fault clearance Annexure-F
SCADA Plots
19 Page 19 of 153 DR Analysis: Annexure-F
Remedial measures taken: Due to problem with PLCC, carrier signal was not sent to GM Navar IPP end during the incident. It is reported by M/s Gamesa Ltd that the PLCC is restored and AR is in service for Points for review: Nandihal-GM Navar Line-1 &2.
(1).Single Bus operation at 220kV Nandhihal Switching SS. (2). Failure of carrier aided protection at GM Navara end for 220kV Nandihal Switching SS GM Navara line-1 (3). Status of A/r in 220kV Nandihal Switching SS -GM Navara line-1. (4). SCADA SoE of 220kV Nandhihal SS and 220kV GMNavar are not available. (5). DR of GM Navara end not furnished for 220kV Nandihal Switching SS -GM Navara line-1 20 Page 20 of 153 94.I.4. Complete Outage of 230kV/132kV Lower JURALAAnnexure-F PH of TSGENCO at 04:23Hrs on 31-10-2020
Weather Protection Normal Maloperation
Gen Loss- 145 MW
• Triggering Incident:Y-N fault caused due to jumper failure on 220kV Jurala SS-Veltoor line at 04:21hrs. • At 04:23 hrs, 220kV Lower Jurala PH-Veltoor line got tripped on operation of DEF protection at 220kV Lower Jurala PH end. Subsequently other 3 connected lines of 220kV Lower Jurala PH got tripped due to operation of distance protection. • Due to tripping of all evacuating lines, running units at 220kV Lower Jurala PH got tripped on operation of over frequency protection. 21 Page 21 of 153 Annexure-F PMU Plots: Delayed fault clearance is 520ms.
SCADA Plots:
Unit No’s Load in MW 1 31.3 2 32.2 3 31.5 4 31.4 5 31.3 6 31.2 22 Page 22 of 153 DR Analysis: Annexure-F
23 Page 23 of 153 Annexure-F 94.I.5. Complete Outage of 220kV Narendra SS of KPTCL at 23:47hrs on 31-10-2020
Weather Single Bus Normal operation
Load Loss: 303MW
• Triggering Incident:Y-phase CT failure at 220kV Bus coupler.
• Zone-1 and Zone-2 differential protection operated at bus bars 1&2 and all the lines and ICTs connected to bus bars got tripped. 24 Page 24 of 153 No Delayed fault clearance Annexure-F PMU plots:
DR Analysis: SCADA plot: 230kV Bus bar-1 of Narendra SS DR Trigger time: - 02:16:480.000 hrs Zone-1 Zone-2 Differential protection
25 Page 25 of 153 Annexure-F Remedial Actions Taken:
1).Now, new CTs have been procured for Bus coupler bay and CT replacement work is under progress. After CT replacement, double bus operation will be restored at Narendra Sub station.
2). GPS time synchronization issue with the Bus Bar Protection scheme was observed from the DR. GPS time synchronizing device is provided at Narendra under R&U works. However SIFANG make Bus Bar Protection relay was not synchronized with GPS clock. Necessary support from OEM is arranged for attending this issue. A compliance report will be furnished to SRPC/SRLDC once above works are attended at Narendra Sub station.
26 Page 26 of 153 94.I.6. Complete Outage of 220kV Vizag Switching StationAnnexure-F and 220kV Parawada SS of APTRANSCO at 16:06 hrs on 07-11-2020
Weather Double Bus with Bus Normal Coupler
220kV Parawada Load Loss- Anark Aluminium 153MW line was under outage.
• Triggering Incident:failure of R-Phase LA of 220kV VSS Gazuwaka_AP line at VSS end. • 400/220kV ICT-1 and 2 at Gajuwaka got tripped on operation of backup OC protection. • At the same time, it was further mentioned that there was snapping of Earth wire of 220kV VSS Gazuwaka_PG line-1 near gantry tower at Gazuwaka_PG end. From PMU plots, delayed fault clearance of 800ms was observed during the event.
27 Page 27 of 153 Annexure-F Delayed fault clearance of around 800ms PMU Plots:
SCADA Plot:
28 Page 28 of 153 Annexure-F DR Analysis:
29 Page 29 of 153 Annexure-F Point for Review:
1. Non operation of Main-1 and Main-2 distance protection of 220kV VSS Gazuwaka_AP line at VSS end. 2. Over voltages in DR of Main-1 and Main-2 at VSS end during fault in 220kV VSS Gazuwaka_AP line. 3. 220kV VSS Gazuwaka_AP line DR not submitted at Gazuwaka_AP. 4. SoE of 220kV VSS is not available in SCADA. Reply from APTRANSCO- RTU panel was old (NELCO make), commissioned in 2001. The Digital input card is not Functioning properly. 5. CVT Make at VSS end. Bus PT or CVT? Zone-2 and reverse zone time delay at 230kV VSS for all connected lines. Remedial Actions Furnished: During Fault condition the voltages sensed by Main-1 & Main-2 relays of 220kV VSS- Gajuwaka feeder at 220kV VSS end were very high compared to the nominal voltages resulting in measurement of high impedances in both the distance relays which in turn may have prevented the tripping of the feeder by the relays at 220kV VSS. The Fault was in Zone 2 Reach from 220kV Gajuwaka SS and it got cleared in Zone2 time from 220kV Gajuwaka SS end. 30 Page 30 of 153 Annexure-F 94.I.7. Complete Outage of 230kV Betam Wind Energy at 12:03 hrs on 12-11-2020
Weather Double bus with bus coupler
Gen Loss- 43 MW
• During battery charger inspection, DC supply to BBP got failed and 230kV TTGS Betam line got tripped at Betam end on Under Voltage St-2 protection operation and DT was received at TTGS end. 31 Page 31 of 153 No fault Annexure-F PMU plots:
Page 32 of 153 Annexure-F Under Voltage Implemented Settings at Betam End:
Page 33 of 153 Annexure-F SCADA Plots: Points for Review:
(1). Enabling of under voltage St-2 protection in 230kV Betam TTGS line at Betam end needs review. (2). Single Bus operation at 230kV Betam Energy
DR analysis:
34 Page 34 of 153 Annexure-F 94.I.8. Complete Outage of 230kV MAPS on 13-11-2020 at 03:10hrs
Weather 230kV MAPS is Main (Sectionalised) bus with transfer bus arrangement.
Generation Loss-220MW
• Triggering Incident:Tripping of the lines 230 kV MAPS-SP Koil line-1 and 230kV MAPS-SP Koil line-2 due to R-N fault in the line sensed at both the ends in zone 1 and at SP Koil end both the lines, auto reclosure was successful and line was holding.
• Subsequently CVT of R-phase of Bhavini feeder had failed and initiated 230 kV Bus-B differential protection resulting in opening of all the breakers connected to Bus-B and bus sectionalizer. 35 Page 35 of 153 PMU Plots: Annexure-F
SCADA Plot: MAPS Generation 250
200
150
100
Power Power (MW) 50
0
-50 3:00:00 3:00:43 3:01:26 3:02:09 3:02:52 3:03:35 3:04:18 3:05:01 3:05:44 3:06:27 3:07:10 3:07:53 3:08:36 3:09:19 3:10:02 3:10:45 3:11:28 3:12:11 3:12:54 3:13:37 3:14:20 3:15:03 3:15:46 3:16:29 3:17:12 3:17:55 3:18:38 3:19:21 Time (hh:mm:ss) 36 Page 36 of 153 Annexure-F Points for review:
1. Non availability of AR at 230kV lines at MAPS needs review 2. DR of 230kV SP Koil is not time synchronised 3. Unavailability of 230kV Bus DR at MAPS needs review
Remedial actions furnished:
CVTs were provided in the R &B phases of BHAVINI feeder. B phase CVT was used for line charge indication. R phase was not used for any protection or metering. Hence R phase CVT was removed and B phase CVT was replaced with spare
37 Page 37 of 153 Annexure-F 94.I.9. Complete Outage of 230kV Checkanurani SS of TANTRANSCO at 13:25 hrs on 16-11-2020
Weather Normal Double Bus with Bus Coupler
Single bus operation a t 230kV Checkanurani SS due to bus coupler CTfailure.
• During antecedent conditions, all elements were connected only to Bus-1 at 230kV Checkanurani SS. • Triggering Incident: failure of R phase CB limb of 230kV Checkanurani Nallamanayakkanpatti line at Checkanurani end. • LBB of 230kV Checkanurani Nallamanayakkanpatti line operated at 230kV
Checkanurani end resulting in the operation of Bus-1 BBP. 38 Page 38 of 153 Annexure-F • ICT#3 was not tripped. Non extension of trip to ICT#3 at 400kV/230kV Madurai SS during 230kV BBP of Bus-1 needs review.
• Due to non-tripping of ICT#3- delayed fault clearance.
PMU Plots: Delayed fault clearance of around 2240ms
39 Page 39 of 153 DR Analysis: Annexure-F
40 Page 40 of 153 Annexure-F Points for Review: (1) Single Bus operation at 230kV Checkanurani SS. (2) Delayed fault clearance: Non-tripping of ICT#3 at 400kV/230kV Madurai SS. It may be noted that trip was not extended to ICT#3 during 230kV BBP operation on 12-03-2020 also. (3) LV side Backup Directional Earth fault protection operation of ICT#3 at 400kV/230kV Madurai SS. Non-directional? (4) Which trip initiated LBB protection of line at 230kV Checkanurani end. (5) DR of 230kV Checkanurani Nallamanayakkanpatti line is still awaited at both the ends.
Remedial Actions Furnished:
(1) In order to set right the above LV3 tripping issue, necessary Line clear was availed at 14.20Hrs (17.11.2020) and tested the Bus bar protection relay and observed that output contact of LV3 was found defective. The same was replaced with available spare contacts and actual tripping extended to LV3 at PGCIL end and found satisfactory.
41 Page 41 of 153 Annexure-F 94.I.10. Complete outage of 220kV Kalamasherry SS of KSEB at 12:41 hrs on 17-11-2020
Single Bus Operation.
Load Loss- 390 MW No (N-1) during antecedent.
• Triggering Incident:B phase to Earth fault in 220kV Kochi_PG Kalamasherry line-1. 220kV Bus Bar Zone-1 protection has operated and all the connecting Feeders/PTRs connected to Bus-1 have tripped. • Fault was sensed in Zone-1 at both the ends. A/r operated at both the ends and line tripped due to persistent fault. • 220kV Kochi_PG Kalamasherry line-2 got tripped on operation of DEF protection at Kochi_PG end and was holding at Kalamasherry end. 42 Page 42 of 153 PMU Plots: Annexure-F
SCADA Plots:
43 Page 43 of 153 DR Analysis: Annexure-F
44 Page 44 of 153 Annexure-F 94.I.11. Complete Outage of 230kV BHAVINI at 22:53hrs on 25-11-2020
Weather • Triggering Incident: Operation of Over voltage stage-1 at Heavy Rains & Bhavini end and all the lines connected to Bhavini got Thunderstorms due to tripped only at this end and the lines were holding at the cyclone (NIVAR) other end.
Load Loss-70 MW
45 Page 45 of 153 PMU Plots: Annexure-F
46 Page 46 of 153 Implemented UV/OV Protection settings at 220kV Bhavini Annexure-F
47 Page 47 of 153 DR Analysis: Annexure-F
48 Page 48 of 153 Annexure-F
49 Page 49 of 153 94.I.12. Complete outage of 220kV Kadra PH of KPCL andAnnexure-F 220kV Karwar SS of KPTCL at 14:00 hrs on 02-12-2020
Weather Normal
Load Loss-39 MW Single Bus Operation
• Triggering Incident:Zone-1 distance protection of 220kV Kadra Kaiga line operated at 220kV Kadra end and LBB got operated since the line was under NFBC during antecedent. • Due to operation of LBB protection, all the elements connected to Bus-1 got tripped at 220kV Kadra.
50 Page 50 of 153 PMU plots: Annexure-F
SCADA plot:
51 Page 51 of 153 Annexure-F DR Analysis:
Points for Review: (1). Fault in 220kV Kadra Kaiga line during NBFC (2). Single bus operation at 220kV Kadra PH.
52 Page 52 of 153 94.I.13. Complete Outage of 400kV SEPC and MultipleAnnexure-F Tripping in 400kV/230kV Thennampatti SS of TANTRANSCO on 05-12-2020 at 02:48hrs
Weather
Rainy
Load Loss- 1.5 MW
BR was out of service from 03-12-202008:53 Hrs after tripping due to PRD relay operation.
• Triggering Incident: Suspected YN fault in 400kV Kanarpatti Tirunelveli line-2
• Subsequent tripping on lines on OV protection operation.
53 Page 53 of 153 Annexure-F
1
2
54 Page 54 of 153 Annexure-F
3
Points for Review:
1. Non-receipt of DT at 400kV SEPC end during the tripping of 400kV SEPC-Thenampatti-1 needs review. 2. OVR grading at 400kV Thennampatti SS needs review. Remedial Actions Furnished: DR mapping at 400kV Thenampatti and 400kV Kanarpatti has been corrected on 14-12-2020 55 Page 55 of 153 PMU plots: Annexure-F
56 Page 56 of 153 Annexure-F
57 Page 57 of 153 94.I.14. Complete Outage of 400kV NLC2 Expansion StationAnnexure-F on 08-12-2020 at 07:52hrs
Weather Double Main Transfer Bus Rain
Generation 1. 400kV NLC2 Expansion unit- loss-190 MW 1 was under outage 2. NLC2 Expansion NLC TS-2 line was under outage
• 400kV NLC2 Expansion NLC TS-2 line was under outage during antecedent conditions due to CT and breaker failure at NLC TS-2 end.
• Triggering Incident: Tripping of 400kV NLC2 Expansion Pugalur line at Pugalur end on DT Receive.
58 Page 58 of 153 Annexure-F Points for review:
Tripping of 400kV NLC2 Expansion Pugalur line due to suspected maloperation of PLCC.
PMU plot: No fault SCADA plot:
59 Page 59 of 153 Annexure-F Remedial Actions Furnished:
ETL-41 panel – Direct trip inputs are getting activated at 70V, Minor DC earth leakage can also cause spurious DT send.
As per OEM suggestion, the Zener diode replacement was carried out in Protection coupler cards. Direct trip input activation observed at 130V after replacement of diodes. The modified cards were replaced at Neyveli end.
60 Page 60 of 153 Annexure-F 94.I.15. Complete Outage of 230kV Villianur substation at 09:20hrs on 09-12-2020
Double Bus with Bus Weather Coupler Heavy Rains Protection Load loss-54 maloperation MW
• Triggering Incident:Tripping of 230/110KV 100MVA Auto Transformer-1 due to operation of Winding Temperature Trip (WTI) at Villianur SS. • Bus-1 and Bus-2 BBP operated at 230kV Villianur SS resulting in the tripping of all connected elements and the same need review. 61 Page 61 of 153 PMU Plots: Annexure-F No fault
Points for review:
1. Tripping of 230/110KV 100MVA Auto Transformer-1 due to operation of Winding Temperature Trip (WTI) 2. BBP operation of Bus-1 and Bus-2 230kV Villianur SS.
62 Page 62 of 153 Annexure-F DR Analysis:
63 Page 63 of 153 Annexure-F 94.I.16. Complete Outage of 230kV/110kV Bahour SS of Pondy at 08:23hrs on 31-12-2020
Double Bus with Bus Weather Coupler Normal
Load loss-100 MW
• Triggering Incident:R phase to B-phase fault in 230KV Bahour Karaikal line at a distance of 2.7KM from 230kV Bahour end and 127KM from Karaikal end.
• At Bahour end, line got tripped on operation of Zone-1 distance protection and at Karaikal end, Zone-2 carrier aided protection operated.
• At the same time, 230kV Bahour Pondy line got tripped only at Pondy end on operation of Zone-1 distance protection and the same needs review. 64 Page 64 of 153 Annexure-F PMU plots: No Delayed fault clearance
DR Analysis:
65 Page 65 of 153 Annexure-F SCADA plot:
Points for review: 1. Tripping of 230kV Bahour Pondy line at 230kV Pondy end for fault in 230KV Bahour Karaikal line. 2. DR of 230KV Bahour Karaikal line at Karaikal end is not furnished. Remedial actions furnished by pondy: 1. M/s Powergrid has been informed to make periodic line patrol in 230KV Bahour Karaikal line. SRLDC e-Mail to SR-2 66 Page 66 of 153 Annexure-F Remedial actions furnished by POWERGRID SR-2:
1. Transplay of the fault was carried out and found relay is operating as per settings only. 2. Issue was referred to M/s Siemens ( OEM) 3. M/s Siemens has suggested to upgrade the firmware from 4.63 to 4.74 to avoid the three pole trippings and POWER SWING issues. 4. As per the recommendation, the firmware upgradation was carried out in spare relay and Transplay also done. After upgradation of firmware, for the same fault, only Z2 pick up is observed. Hence after confirmation, firmware upgradation was carried out for Siemens relay of Pondy- Bahoor line. 5. Further complete testing files and DEX files forwarded to M/s Siemens to identify the firmware issues with the older version. 6. Similar firmware upgradation is being taken up for all old version relays of M/s Siemens.
67 Page 67 of 153 Annexure-F
Details of Grid Incidents
68 Page 68 of 153 Annexure-F 94.II.1. Tripping of 220 kV Regulpadu- Alipur Line on 01-Oct-2020 at 14:07hrs
• Triggering incident: Interchanging the phase sequence (online) from RYB to BRY. • One of the trip contacts was shorted which resulted in tripping of the line at Alipur end. Tripping due to operational • Regulapadu end line did not trip. error
Till arrangements for suitable correction in the primary circuit is made at Alipur SS end, the secondary side correction is envisaged by interchanging the phase sequence in the secondary side from RYB to BRY to match with the Ragalapadu S/S end phase sequence. At 14.07 Hrs: Line tripped accidently While carrying out wiring modifications. 69 Page 69 of 153 Annexure-F 94.II.2. Multiple Tripping at 400kV Vijayawada SS on 03-Oct-2020 at 14:04hrs Weather Normal • Triggering Incident: R phase to Earth fault in 400kV Vijayawada Sattenapalli line. • At Vijayawada end, Zone-2 carrier aided protection operated and at Sattenapalli end, Zone-1 distance protection operated. • A/r operated at both the ends and line tripped due to persistent fault. • At the same time, 400kV Vijayawada VTPS IV line-2 tripped only at Vijayawada end due to suspected maloperation of Main-2 distance protection and the same needs review.
Remedial measures taken:
Old Main-2 relay ABB make Model: REL100 retrofitted with new relay ABB make, Model: REL 670 relay on 02.01.2021 at Vijayawada end.
70 Page 70 of 153 DR Analysis: Annexure-F 400kV Vijayawada Sattenapalli line: 400kV Vijayawada End: 400kV Sattenapalli End: DR trigger time-14:04:56:212hrs DR trigger time-14:04:56.205hrs RN fault, RN fault, Ifault-3.2kA Ifault-6.8kA Zone-2, Zone-1, carrier receive carrier send A/r operated A/r operated RN fault RN fault ToR, ToR, 3ph trip. 3ph trip. 400kV Vijayawada VTPS IV Line 2: 400kV Vijayawada End: DR trigger time-14:04:56:220hrs RN fault, Ifault-1.5kA R and Y Main pole open
71 Page 71 of 153 Annexure-F 94.II.3.Tripping of HVDC Gajuwaka Pole 1 AND HVDC Gajuwaka Pole 2 on 06-Oct-2020 at 18:13:00 Hrs
Weather Antecedent power flow in BTB Gazuwakak Pole-1 and 2- 400MW. Normal
Total Power Flow: 400 MW E to S Pole - 1: 250 MW E to S Pole - 2: 150 MW E to S
• Triggering Incident: Failure of Yph CT of South side CWD30Q50 Bay. • BTB HVDC Gazuwaka Pole-1 got tripped on operation of Y Block protection due to disturbance in Inverter side because of sustained commutation failure due to loss of AC voltage during the failue of Yph CT of South side CWD30Q50 Bay.
45 Page 72 of 153 PMU Plots Annexure-F
SCADA Plot:
73 Page 73 of 153 DR Analysis: Annexure-F
BTB HVDC Gajuwaka Pole-1: BTB HVDC Gajuwaka Pole-2: DR trigger time-18:08:23.043hrs DR trigger time- 18:08:23.041hrs DR is partial. Commutation Failure CF_IND
Remedial Actions Taken: Pole 1 South Tie Bay CWD 30 bay was isolated by opening the Bay Isolators. Damaged CT (BHEL make) relaced with spare CT (CGL make).
74 Page 74 of 153 Annexure-F 94.II.4. Tripping of 220kV Srisailam Right Bank to Nagarjunasagar TS1 Line
Tripping date Reason and time 07-Oct-20 Triggering incident was R-phase to ground fault in the line at a 10:37 distance of 0.2 km. from Srisailam end due to SRC insulator 01-Dec-20 flashover. Line tripped on Zone-1 distance protection at Srisailam 09:20 end and Zone-2, distance protection at Nagarjunsagar end. Auto reclose in the line is not in service since the line connects two generating stations. Non operation of Z2 carrier aided protection at N'sagar end needs review.
• Findings and remedial actions taken shall be furnished.
75 Page 75 of 153 Annexure-F 94.II.5. Tripping of 230kV Bus-1 at 400/ 230kV Tirunelveli station of PGCIL on 12-Oct-20 at 13:45Hrs
Double Bus
Connectivity at 230kV 230kV Tirunelvelli (Abhishekpatty) SS during the event.
• Triggering Incident:Y-B phase fault in 230kV Tirunelveli - Udayathur line. • LBB of 230kV Bus-1 at Tirunelveli station operated due to breaker stuck position resulting in tripping of all Bus-1 connected elements. 76 Page 76 of 153 Annexure-F PMU plots:
77 Page 77 of 153 Annexure-F DR Analysis:
78 Page 78 of 153 Annexure-F
Remedial Actions Taken:
79 Page 79 of 153 Annexure-F 94.II.6. Tripping of 400/230 kV ICT-1 at Udumalpet on 14-Oct-20 at 03:49 Hrs
• ICT got tripped due to suspected maloperation of PRV protection due to contact failure in the device.
• Findings and remedial actions taken shall be furnished.
DR Analysis:
DR trigger time- 03:49:39.234 hrs PRV_TRIP
80 Page 80 of 153 94.II.7. Tripping of 400kV Dhoni - Guttur Line Annexure-Fon 17-Oct-20 at 16:12 Hrs
• Line tripped only at Guttur end on operation of CTD while DR Not available replacing CB panel DC source-2 fuses.
Remedial Actions Furnished:
Maintenance Engineers working in Guttur have been advised to follow the Standard Operating Procedure to avoid trippings due to manual errors.
81 Page 81 of 153 Annexure-F 94.II.8. Tripping of 400/220 kV ICT-1 at Raichur on 21-Oct-20 at 15:09 Hrs
• ICT#1 at RTPS got tripped due to suspected maloperation of Mal-operation Buccholz protection. DR not • Findings and remedial actions taken shall be furnished. triggered
Weather
82 Page 82 of 153 94.II.9. Tripping of 400/220 kV ICT-3 at TrichurAnnexure-F on 25-Oct-20 at 15:17 Hrs
• 110kV Madakkathara-Valappad feeder tripped on distance DR not protection. furnished • Simultaneously ICT#3 tripped on action of tertiary Earth fault protection
Remedial Actions Furnished:
• Instruction given to ensure that earthing shall not be provided on both sides of the tertiary Grounding CT when the same is kept out of service. • Triggering of Disturbance record set to be initiated when tertiary earth fault protection acts.
83 Page 83 of 153 Annexure-F
84 Page 84 of 153 94.II.10. Multiple Tripping in 400/230/110kV KamuthiAnnexure-F SS on 25-Oct-20 at 07:07 Hrs
230kV bus was operating in • Triggering incident: bus split condition. • Inadvertent opening of 230kV bus coupler at 06:03hrs. • Because of this ICT-1 (400/230KV), ICT-2(400/230KV) & ICT-4(400/110KV) tripped at 6.18Hrs • ICT-3 (400/110KV) tripped at 7.02Hrs • ICT-5(400/110KV) tripped at 7.07Hrs due to over flux protection.
85 Page 85 of 153 Annexure-F SCADA plots:
86 Page 86 of 153 Annexure-F DR Analysis:
87 Page 87 of 153 Annexure-F 94.II.11. Tripping of 400/230 kV ICT-3 at S'PUDUR
DRs not available .Tripping date Reason and time 28-Oct-20 400/220kV ICT-3 at Sriperumbudur tripped on operation of B-phase 08:07 unit PRV auxiliary protection due to problem in the PRV. Its also 16-Nov-20 reported that there was no oil spurt out observed in the PRV. 10:13
• Findings and remedial actions taken shall be furnished
Remedial Measures: • Transformer oil test (BOTTOM oil sample) done and was found in order.
88 Page 88 of 153 Annexure-F 94.II.12. Tripping of 400/220 kV ICT-3 at Malkaram on 28-Oct-20 at 11:29 Hrs
• LC of bus-1 for general maintenance works was availed on the day of the event. • While testing of metering circuit of ICT-4 bay, trip signal was extended by mistake to Mallkaram ICT-3 resulting in tripping of the ICT.
Tripping due to operational DR Analysis: error
DR Trigger time: 11:29:17.593 Hrs L8 HV Grp-A OPTD
89 Page 89 of 153 Annexure-F 94.II.13. Tripping of 400/230kV ICT#2 at Thiruvallam
Tripping date Reason and time
01-Nov-20 ICT#2 and 400kV Alamathy - Thiruvalam line-2 are in the same dia at 400kV 10:57 Thiruvalam end. During antecedent conditions, Main breaker of ICT#2 at 01-Nov-20 Thiruvalam end was under outage due to CT replacement works. Triggering 12:17 incident was R phase to Earth fault in 400kV Alamathy - Thiruvalam line-2. A/r operated successfully at both the ends and line was holding. At Thiruvalam end, A/r of main breaker only operated and tie breaker tripped. Due to tripping of tie breaker at Thiruvalm end, ICT#2 also tripped.
02-Nov-20 ICT#2 and 400kV Alamathy - Thiruvalam line-2 are in the same dia at 400kV 11:32 Thiruvalam end. As per the report submitted, during antecedent conditions, Main breaker of ICT#2 at Thiruvalam end was under outage due to CT replacement works. Triggering incident was R phase to Earth fault. Fault was sensed in Zone-1 at both the ends. A/r operated successfully at both the ends and line tripped due to persistent fault. At Thiruvalam end, A/r tie breaker did not operate. Due to tripping of tie breaker at Thiruvalam end, ICT#2 also tripped. 90 Page 90 of 153 Annexure-F Tripping date Reason and time 25-Nov-20 ICT#2 and 400kV Alamathy - Thiruvalam line-2 are in the same dia at 21:26 400kV Thiruvalam end. As per the report submitted, during antecedent conditions, Main breaker of ICT#2 at Thiruvalam end was under outage due to CT replacement works. Triggering incident was operation of OV Stage-1 protection at Alamathy end and DT was received at Tiruvalam end. On receiving DT at Thiruvalam end, ICT#2 also tripped due to tripping of tie breaker. As per the DR analysis, Voltages observed at Alamathy end are Vr251kV: Vy-251kV. Tripping needs review.
91 Page 91 of 153 DR Analysis: Annexure-F i. On 01-Nov-20 at 10:57hrs 400kV Alamathy Thiruvallam line-2:
400kV Thiruvallam End:
DR trigger time-10:55:01.223hrs RN fault Z1, carrier receive A/r operated ii. On 01-Nov-20 12:17hrs 400kV Alamathy Thiruvallam line-2:
400kV Alamathy End: 400kV Thiruvallam End:
DR trigger time-12:09:13.382hrs DR trigger time-10:55:01.223hrs RN fault, RN fault Z1, Zone-1 carrier receive A/r operated A/r operated RN fault, Zone-1 ToR 3ph trip
92 Page 92 of 153 DR Analysis: Annexure-F
iii. On 02-Nov-20 at 11:32hrs 400kV Alamathy Thiruvallam line-2:
400kV Alamathy End: 400kV Thiruvallam End:
DR trigger time-11:31:53.195hrs DR trigger time- 11:30:13.989hrs RN fault, RN fault, Zone-1 Zone-1 A/r operated A/r operated RN fault, RN fault, Zone-1 Zone-1 ToR ToR 3ph trip 3ph trip iv. On 25-Nov-20 21:26hrs 400/230 Kv ICT 2 AT Thiruvellam: : DR trigger time: 21:26:20.049hrs DT recieved
93 Page 93 of 153 94.II.14.Tripping of 220kV Bus-1 and Bus-2 at NelloreAnnexure-F SS of APTRANSCO on 02-Nov-20 at 22:27Hrs
400/220/132 KV Manubolu SS
400 KV 220 KV BUS Bus-1 Double main 315 MVA Weather ICT-1 220 KV configuration Bus-2 315 MVA ICT-2 220 KV 220 KV Nellore Transfer Bus-2 2
315 MVA ICT-3 Normal 3
BUS Coupler 220 KV CB Rachaguneri 220 KV Sullurpet 1
1
Load Loss- 3 220 KV R O Pilot string Sullurpet insulator flash 200 MW over 2 220 KV Rachaguneri 2 132 KV 100 MVA PTR-3 Bus
220 KV Nellore 1
100 MVA PTR-2
100 MVA PTR-1
132 KV Gudur 1
2
132 KV Rapur 1
2
132 KV Chendodu
94 Page 94 of 153 Annexure-F • Triggering incident: Failure of R-phase pilot string insulator at the bottom of 220kV Bus-2 section between 220kV Nellore-3 and 220kV Sullurpet-1 line bays at 220kV Manubolu SS. • BBP of Bus-2 operated (400/220kV ICT-2 and 3). • non-opening of 220kV Bus coupler breaker • All lines connected at 220kV Manubolu Bus-1 got tripped at remote end on operation of Zone-2. • 400/220kV ICT-1 connected at Manubolu Bus-1 got tripped on operation of HV side backup E/F protection.
PMU Plots: Delayed fault clearance of 640ms
95 Page 95 of 153 Annexure-F DR analysis:
96 Page 96 of 153 Annexure-F DR analysis:
Points for review:
1. Non opening of Bus Coupler breaker during Bus-2 BBP operation. 2. Non availability of ICT#1 DR for operation of backup OC protection. 3. Tripping of 220kV Manubolu-Nellore-3 on Zone-1 at Manubolu end.
97 Page 97 of 153 Annexure-F Remedial meaures taken: 1. The Bus shut down was availed on 220KV Bus-2 on 03-11-2020 and the suspected anti fog insulator strings of M/s. WS make were replaced with the available 120KN healthy anti fog disc insulators of M/s. ABI make and 220KV Bus-2 was charged at 18:30hrs on 03-11-2020 2. The reasons for non-tripping of 220KV Bus coupler breaker was explored and found that, positive wire from 220KV Bus coupler panel to 220KV Bus bar protection panel got open at the crimped lug at Bus coupler panel. Hence the master trip relay pertaining to Bus coupler in Bus bar protection panel was not operated causing non operation of Bus coupler breaker. 3. The same was rectified, checked the operations of the Bus coupler breaker and found satisfactory. After ensuring the healthiness of control circuit, Bus coupler was taken into service at 12:24hrs on 03-11-2020.
98 Page 98 of 153 Annexure-F 94.II.15. Tripping of 400/220kV ICT-4 at Shankarpally on 07-Nov- 20 at 11:47 Hrs
• ICT#4 at Shankarapalli tripped due to suspected maloperation of PRV protection due to moisture ingress and the same needs review.
DR Analysis: Protection ICT#4 at Shankarapalli End: mal-operation DR triggering time-11:47:52.561hrs PRV Trip
Remedial actions:
• Cleaned the moisture and charged ICT
Page 99 of 153 Annexure-F 94.II.16. Tripping of 400 kV BTPS-JSW Toranagallu on 08-Nov-20 at 21:45Hrs
Weather Normal
• Line tripped on operation of OV St-1 protection operated at BTPS end and DT was received at JSW end.
• As per the DR of BTPS end, voltages observed are:Vr-242kV, Vy-239kV and Vb- 235kV. Since the voltages at BTPS end are within limits, operation of OV St-1 protection at BTPS end needs review.
DR Analysis:
400kV BTPS END: 400kV JSW END:
DR TRIGGER TIME:21:45:08.889hrs DR TRIGGER TIME: 21:45:18.947hrs OVR stage-1 protection DT received 86A A/B OPERATED
100 Page 100 of 153 Annexure-F 94.II.17.Tripping of Bus-1 at 220kV Narsapur SS of TSTRANSCO on 10-Nov-20 at 01:13 Hrs
Load Loss-6.4 Double Bus MW configuration
• Triggering incident :Y-Phase Suspension Insulator string on LV side of ICT-1 near 220kV Bus 1. • 220kV Bus Bar Zone-1 protection has operated and all the connecting Feeders/PTRs connected to Bus-1 have tripped. • From field inspection it is observed that there was a bird nest on the boom above this suspension insulator string.Page 101 of 153 Annexure-F PMU plots:
No delayed fault clearance
102 Page 102 of 153 Annexure-F DR Analysis:
103 Page 103 of 153 Annexure-F 94.II.18.Tripping of 400/220 kV ICT-3 at Hoody 13-Nov-20 at 15:02 Hrs
Weather Normal
• Triggering incident :Failure of 4CX25sqmm Copper Cable running from battery charger (in the control room) to DCDB panel in Kiosk No.7.
• This resulted in DC current leakage and LV side CB opened. No load was affected as 500MVA ICT1 & ICT3 are in parallel. Tripping needs review.
Remedial actions:
The problem was attended by isolating the faulty portion of the cable.
Page 104 of 153 Annexure-F 94.II.19.Tripping of 400kV Kalpakka Gazuwaka Line-1
Weather
Normal
Tripping date Reason and time 13-Nov-20 As per the report submitted, triggering incident was fault in 400kV 11:12 KV Kota Hinduja line. 400kV Kalpakka - Gazuwaka line tripped only 16-Nov-20 at Gazuwaka end due to suspected mal operation of Main2 12:17 (Schneider make P546 type) SoTF function and the same needs review.
Remedial actions:
APTRANSCO: Matter was referred to M/s.Schneider (who commissioned these relays at 400KV PGCIL SS) for verification and confirmation of healthiness of scheme configuration to avoid mal operations.
105 Page 105 of 153 Annexure-F DR Analysis:
i. On 13-Nov-2020 400kV Gazuwaka End: DR trigger time-11:06:24.043hrs BN fault A/r operated Zone-3 Main-1 trip was also observed from DR. ii. On 16-Nov-2020
400kV Gazuwaka End: DR trigger time-12:17:06.907hrs BN fault A/r operated Zone-3 Main-1 trip was also observed from DR.
106 Page 106 of 153 Annexure-F 94.II.20.Tripping of 220kV Bus-2 at Srisailam Right Bank of APGENCO on 16-Nov-20 at 20:26hrs
Weather Generator Unit-I is Under LC. Normal
107 Page 107 of 153 Annexure-F
• During charging of Unit-5 at 220kV Srisailam RB, R phase circuit breaker of GT-5 got failed and Bus Bar Protection of Bus-1 operated resulting in the tripping of all the elements connected to bus-1. • From the DR of Generator Unit-5 and 220kV Srisailam Dindi line, LBB operation was also observed. At the same time, 220kV Srisailam RB-Nsagar TS-1 feeder connected to Bus-2 at Srisailam RB tripped only at Nsagar end on operation of DEF protection and the same needs review. PMU plots: PMU data at Srisailam LB was not available during this event.
PMU Voltage plot at 19:09 hrs: 108 Page 108 of 153 Annexure-F PMU Voltage and Sequence Current Plot at 20:26hrs:
SCADA plots:
109 Page 109 of 153 Annexure-F DR Analysis:
110 Page 110 of 153 Annexure-F 94.II.21.Tripping of 400/230 kV ICT-2 at Pugalur on 17-Nov-20 at 17:27hrs
• 400/230kV ICT-2 at Pugalur tripped on operation of Buchholtz relay.
• Findings and remedial actions taken shall be furnished.
DR Analysis: ICT-2 at 400kV Pugalur end:
DR Trigger time:17:26:58.270 Hrs Bucholtz TRIP
111 Page 111 of 153 Annexure-F 94.II.22.Tripping of 400/230 kV ICT-1 and 2 at Madurai on 17-Nov-20 at 17:27hrs
Weather • it is suspected that 400/230 kV ICT-1 and 2 at Madurai got tripped due to testing of 230kV BBP scheme at 230kV Checkanuarani TANTRANSCO end.
• However, as per the information furnished by TANTRANSCO, leads of all bays were disconnected prior to testing.
• It was further mentioned that there was no possibility to extend the trip signal. However, from ICT#1 and 2 DRs, 230kV BBP operated signal was observed. Tripping needs review. DR Analysis:
400/230 kV ICT-1 at Madurai: 400/230 kV ICT-2 at Madurai: DR trigger time- 16:23:43.076hrs DR trigger time-16:23:43.076hrs 230KV BB_OPD. 230KV BB_OPD 112 Page 112 of 153 Annexure-F 94.II.23.Tripping of Bus-1 at 230kV Trichy TN SS of TANTRANSCO on 17-Nov-20 at 00:01hrs
At Trichy SS 230kV bus bar was in single bus configuration Weather and all the elements were connected to bus-1. Normal
• Triggering incident: B-N fault in the 230kV Trichy-Alundur line-1. Fault was sensed in zone-1 at Trichy end. • Due to non-opening of B pole CB at 230kV Trichy end, LBB operated and all the 113 lines connected to 230kV Bus-1Pagegot tripped 113 of on153operation of BBP protection. PMU plots: Annexure-F
DR Analysis:
114 Page 114 of 153 Annexure-F Remedial Actions Furnished:
230kV Trichy-Alandur line-1 breaker at Trichy end is taken under LC on 17.11.2020 and mechanism /overhauling work is in progress
Points for Review: 1. Single bus operation of 230kV bus at Trichy needs review. 2. Non-opening of 230kV Trichy-Alandur line-1 CB at 230kV Trichy end needs review. 3. 220kV Line DRs not in order.
115 Page 115 of 153 Annexure-F 94.II.24.Tripping of 400 kV Vemagiri - GMR 2 on 21-Nov-20 at 11:34hrs
Weather Normal DR not furnished
• At GMR end because of maloperation of main-1 relay DT was sent and
• Line was holding at Vemagiri end.
• Findings and remedial actions taken shall be furnished.
116 Page 116 of 153 Annexure-F 94.II.25.Tripping of 400kV/220kV Julurupadu-ICT-1 on 26-Nov-20 at 16:02hrs
Weather DR not available Normal
• Triggering incident: DC earth leakeage in the cable connected from DC Distribution board to Transformer. Because of this LV side CB got tripped.
• Findings and remedial actions taken shall be furnished.
117 Page 117 of 153 Annexure-F 94.II.26.Tripping of 220kV Bus-2 at Shankarapalli SS of TSTRANSCO on 26-Nov-20 at 07:57hrs
Weather Single Line Diagram of 400/220kV Shankarpally SS on 26-11-2020 at 07:57hrs
Normal 220kV Tandur 400kV Bus
220kV Kethireddypalli
1 2 3 4 315MVA 315MVA 315MVA 500MVA
220kV BUS-2
BC 220kV BUS-1
R phase jumper 2 1 snapped 2 1 2 1 2 1 220kV Gachibowli 220kV Sadasivpet
220kV Yeddumailaram 220kV Parigi 118 Page 118 of 153 Annexure-F
• Triggering incident:R-N fault in the 220kV Shankarpally-Parigiri line-1. • Fault was sensed in zone-1 at Shankarpally end. • Due to non-opening of R pole CB at 220kV Shankarpally end, LBB operated and all the lines connected to 220kV Bus-2 got tripped on operation of BBP protection.
Delayed Fault clearance- 200ms PMU plots:
119 Page 119 of 153 SCADA plots: Annexure-F
Points for review:
1. Non-opening of 220kV Shankarpally- DR Analysis: Parigiri-1 breaker at Shankarpalli end needs review. 2. DR of 220kV Shankarpally-Parigiri-1 at Parigiri end is not time synchronized with GPS 3. DR of 220kV Shankarpally-Parigiri-1 submitted at Parigiri end is incomplete/partial
120 Page 120 of 153 Annexure-F 94.II.27.Tripping of 400 kV Srisailam - Dindi -1on 28-Nov-20 at 17:21hrs
Weather
Cloudy • Triggering incident: Recieving DT signal at Dindi end because of Relay maloperation at Srisailam end.
• Line tripped only at Dindi end.
• Findings and remedial actions taken shall be furnished.
DR Analysis:
400kV Dindi end: 400kV Srisailam end: DR trigger time:16:43.679hrs Line was holding DT received
121 Page 121 of 153 Annexure-F 94.II.28.Multiple Tripping at 400kV Jindal TPS of JSWEL and 400kV BTPS of KPCL on 29-Nov-20 at 13:16hrs
Weather Double main and Cloudy and transfer scheme drizzling
Load Loss-213 MW
Generation Loss-1640 MW
• Triggering incident: Fault in 400kV GIS bus compartment at JSW TORANAGALLU 13:16:28 hrs. • BBP operated at JSW end. • BTPS connected lines tripped.
122 Page 122 of 153 Annexure-F
220kV & 400kV Jindal 400 kV Jindal TPS Generation outage due to (2 * 130 + 4 * 300 ) 400 kV R-N fault since 400 kV Hiriyur 28-11-2020 at Guttu 06:21hrs. r
220 kV Lingapur 400kV BTPS Generation (2*500+1*700 MW) To Nelamangala, 400 kV BTPS Zone-4 Pavagada Mysore 220 kV Zone-2 R-N Fault Jindal 400 kV Bellary PS Zone-2 R-N Fault
To YTPS, Pavagada RTPS Jaglur To Raichur_PG, outage to attend Munirabad gas pressure low Mahabubnagar alarm since 27-11- Units#1 and 2 at BTPS (906 MW) tripped 2020 at 06:27hrs. due to electrical side problem.
Page 123 of 153 Annexure-F
Page 124 of 153 Annexure-F
PMU Plot:
SCADA Plot:
Page 125 of 153 Annexure-F 94.II.29.Tripping of 220kVTalapally - Nagarjunasagar_TS -3
Date and time of Reason triping 01-Dec-20 15:45 As per the report submitted, triggering incident was PT fuse failure at N'sagar end. Line tripped only at N'sagar end and was holding at Tallapally end
03-Dec-20 21:30 As per the report submitted, triggering incident was R-N fault in the line. Line tripped only at N'sagar end because of suspected maloperation of DEF protection. Tripping needs review.
06-Dec-20 20:00 As per the report submitted, triggering incident was R-N fault in the line. Line tripped only at N'sagar end because of suspected maloperation of DEF protection and the same needs review.
126 Page 126 of 153 Annexure-F Date and time of Reason triping 20-Dec-20 21:25 As per the report submitted, triggering incident was R-N fault in the line. At N’sagar end, DEF operated and line tripped only at this end. Line was holding at Tallapally end. Tripping needs review. 23-Dec-20 00:16 As per the report submitted, triggering incident was R-N fault in the line.DEF operated at N’sagar end and the line tripped only at this end. Line was holding at Tallapally end. Tripping needs review.
DR Analysis: i. On 03-Dec-2020 at 21:30:00 220kV Tallapally end: 220kV N'sagar end: Line was holding DR trigger time:21:20:58.592hrs R-N fault Ifault=710A Earth fault protection operated 3 phase trip From the EL : At 21:21:25.430hrs DEF operated. 127 Page 127 of 153 ii. On 06-Dec-20 at 20:00 Annexure-F 220kV Tallapally end: 220kV N'sagar end: Line was holding DR trigger time:20:00:28.118hrs R-N fault Ifault=526A 3 phase trip DR is incomplete. From the EL : At 20:00:56.362hrs DEF operated.
iii. On 20-Dec-20 at 21:25 220kV Tallapally end: 220kV N'sagar end: Line was holding DR trigger time:21:25:27.233hrs R-N fault I fault=486A DEF operated 3 phase trip
128 Page 128 of 153 Annexure-F iv. On 23-Dec-20 at 00:16hrs 220kV Tallapally end: 220kV N'sagar end: Line was holding DR trigger time:21:25:27.233hrs R-N fault DEF operated I fault=486A 3 phase trip
129 Page 129 of 153 Annexure-F 94.II.30.Multiple Tripping in 400kV Gajwel SS of TSTRANSCO on 02-Dec-20 at o3:07hrs
Weather Normal
• Triggering incident:Y-N fault in 400kV Gajwel-Narsapur line. • Fault was sensed in zone-1 protection at Narsapur end and carrier aided zone-2 protection operated at Gajwel end. • A/R operated and successful at both the ends. • At the same time, 400KV Gajwel-Narsapur-1 line tripped at Gajwel end only on suspected maloperation of SOTF and the same needs review.
130 Page 130 of 153 Annexure-F DR Analysis:
i. 400kV Gajwel-Narsapur line: 400kV Gajwel end: 400kV Narsapur end: DR trigger time:03:03:27.906hrs DR trigger time:03:04:27.793hrs Y-N fault Y-N fault carrier aided zone-2 zone-1 A/r operated and succesful A/r operated and succesful
ii. 400kV Gajwel-Chandalapur line: 400kV Gajwel end: 400kV Chandalapur end: DR trigger time:03:03:27.926hrs Line was holding SOTF trip
131 Page 131 of 153 Annexure-F 94.II.31. Tripping of 400/220 kV ICT-1 at Dichpally on 04-Dec-20 at 15:42hrs
Weather Normal
• 400kV/220kV ICT#1 at Dichipalli got tripped on operation of Differential protection due to testing of tie CT (same dia) wiring by MRT wing.
• Tripping needs review
DR Analysis:
ICT-1 AT DICHPALLY: DR trigger time15:40:20.121hrs Differential Trip
Remedial Actions: Instructed MRT Wing to take proper precautions while testing.
132 Page 132 of 153 Annexure-F 94.II.32. Multiple Tripping at 220kV Sabarigiri GS on 04-Dec-20 at 18:10hrs
Weather • Triggering incident: 3 phase fault in the line at a distance of 3.4kM from Sabarigiri end. • At Sabarigiri end, Zone-1 distance protection operated and resulted in 3 phase trip. • At Theni end, zone-2 distance protection operated and resulted in 3 phase trip. • Non operation on carrier aided protection needs review. • Tripping of unit -5 needs review. DR Analysis:
220kV Sabarigiri end: 220kV Theni end: DR trigger time:18:10:11.016hrs DR trigger time:18:10:44.285hrs 3 phase fault 3 phase fault zone-1 zone-2 3 phase trip 3 phase trip
133 Page 133 of 153 • Non operation of carrier aided protection of 220kY Sabarigiri-Theni feedersAnnexure-F was due to the terminal connection issue in the PLCC panel at Theni end.
• Kochu Pamba 66 kV feeder also tripped with R- phase to earth indication.
• Unit No. 5 tripped simultaneously on non-lock out with cooling water flow low indication, and has gone to turbine operation (spinning) mode. Remedial Actions Taken: • Steps are initiated to provide distance relay for 66kV Kochu Pamba feeder. • The logic scheme of Unit#5 is being modified to prevent unwanted tripping during momentary loss of cooling water flow. No issues were found on the-LT supply scheme of Unit#5auxiliary. • Carrier aided protection iwas verified and corrected on 26.12.2020.
134 Page 134 of 153 Annexure-F 94.II.33. Tripping of 400KV/110KV Thennampatty-ICT - 3 on 07-Dec-20 at 03:56hrs
Weather • Triggering incident: operation of PRV-2 trip protection due to heavy rain.
• Findings and remedial actions taken shall be furnished.
DR Analysis:
400/110kV Thennampatty ICT: DR Trigger time:03:56:02.971hrs PRV- 2_TRIP
135 Page 135 of 153 Annexure-F 94.II.34. Tripping of 400kV Bus-1 and Bus-2 at 400kV/230kV NLC TS-2 Generating Station on 07-Dec-20 at 18:59hrs
Weather Double main and Normal transfer scheme
Generation Loss-300 MW
• As per the report submitted it was mentioned that there was failure of Y-phase pole of Transfer Bus Coupler and Y-phase and B-phase CT of Transfer Bus Coupler at 400kV NLC TS-2. • It was further mentioned that there was operation of 400kV BBP of Bus-1 and Bus- 2 at NLC TS-2 resulting in de-energisation of 400kV bus of 400kV/230kV NLCTS-2.
136 Page 136 of 153 • 230kV NLC TS-2 was intact during the event. Annexure-F
• But from DR analysis of all the elements and PMU plots, three different events were observed and tripping needs further review.
• Report/details furnished by NLC TS-2 is incomplete/insufficient for further analysis.
PMU plots:
137 Page 137 of 153 Annexure-F
138 Page 138 of 153 SCADA plots: Annexure-F
DR Analysis:
139 Page 139 of 153 Annexure-F
140 Page 140 of 153 Annexure-F
141 Page 141 of 153 Annexure-F 94.II.35. Tripping of 220kV Bus-1 at 400kV/220kV Guttur SS of KPTCL on 16-Dec-20 at 10:17hrs
Weather
Single Bus Operation Prefault Condition: At 220kV Guttur, due to replacement work of Neelagunda line CB, all elements except Neelagunda were connected to Bus-1. Neelagunda line was charged through Bus Coupler CB. • Triggering event: B-N fault in 400kV Kaiga-Guttur line-2 • Zone-1 at Kaiga end with DT being sent to the remote end and Zone-2 with carrier aided trip sensed at Guttur end. • A/R at Kaiga end did not operate. • 400/220kV Kaiga ICT-1 got tripped due to operation of TEED protection. • 220kV Guttur-Jogihalli line in Main 1 external LBB operated
142 Page 142 of 153 PMU plots: Annexure-F
SCADA plots:
143 Page 143 of 153 Annexure-F DR Analysis:
144 Page 144 of 153 Annexure-F 94.II.36. Tripping of HVDC Talcher Kolar Pole1 and Multiple Tripping at 400kV Kolar SS on 20-Dec-20 at 21:25hrs
Weather
Normal
Bus Reactor at 400kV Kolar SS was in service Load Loss-635 MW(Due to SPS operation)
• Antecedent power flow in Bipole was 1560MW.
145 Page 145 of 153 Annexure-F Brief details: • Pole-1 of HVDC Talcher-Kolar got tripped due to problem in valve cooling system at Talcher end and ESOF was received at Kolar end. • After the tripping of Pole-1, Pole-2 had initiated the changeover to metallic return, however, the sequence had failed. • Hence Pole-2 subsequently went in to Ground Return mode with Power flow of 145MW at Kolar end due to the electrode current limitation. • SPS of HVDC Talcher-Kolar Trip 1 (TK-1) got operated since the loss of power was more than 500MW immediately after the tripping of Pole-1, resulting in load relief of 635MW. • After the tripping of Pole-1, rise in 400kV Kolar voltage was observed and all connected 400kV lines at Kolar except 400kV Kolar Hoody line-1 got tripped on operation of OV St-1 protection at Kolar end and DT was received at remote ends. AC filter bank-1 & 3 also got tripped during the event.
146 Page 146 of 153 Annexure-F SPS operation details: SPS Trip Signal-1 operated at Kolar end since total power loss was more than 1000 MW (Pole-2 went to Ground Return mode with power flow of 145 MW at Kolar end). Total load relief as per information from constituents is 635 MW. Load relief details are given below:
Talcher-Kolar SPS operation at 21:25 Hrs on 20-12-2020 State Trip Signal -1 designed Trip Signal -1 Actual Load relief (in MW) Load relief (in MW) Andhra Pradesh 230 160 Telangana 0 0 Karnataka 250 233 Tamil Nadu 356 242 Kerala 0 0 Total 836 635
147 Page 147 of 153 Annexure-F PMU plots:
148 Page 148 of 153 Annexure-F
DR Analysis:
149 Page 149 of 153 Annexure-F
150 Page 150 of 153 Annexure-F
151 Page 151 of 153 OVR Grading Issues in 400kV Kolar SS: Annexure-F Present sequence of tripping is not serving the purpose of reducing the Bus voltage. It can be observed that there is a rise in Bus voltage after tripping of Thiruvelam line and Somanahalli line which has further worsened the situation. O/V grading sequence needs to be set so that tripping of a line reduces the Bus voltage. To avoid sequential tripping of 400kV lines at Kolar due to OV, as a precautionary measure it is necessary to review the OV grading at 400kV Kolar SS. Similar tripping of 400kV Kolar lines were observed on 16-07-2020 and 19- 09-2020 (Note: 400kV Hoody Yelahanka lines were under outage) MW and MVAr flows of 400kV Kolar lines prior to the events on 16-07-2020 and 19-09-2020 along with PMU voltage plots are given below. 01:58hrs on 05:02hrs on 21:20hrs on 16-07-2020 19-09-2020 20-12-2020 Sno. List of Lines P in Q in P in Q in Q in P in MW MW MVAr MW MVAr MVAr 1 400kV Kolar Thiruvalam Line -197 56 205 -78 143 -21 2 400kV Kolar Somanahalli Line -169 40 170 -30 145 Suspect 3 400kV Kolar NP Kunta Line 0 0 0 0 -153 -18 4 400kV Kolar Hosur Line-1 -5 52 100 10 212 -31 5 400kV Kolar Hosur Line-2 -5 53 95 13 206 -24 6 400kV Kolar Hoody Line-1 337 -66 324 -82 424 0 7 400kV Kolar Hoody Line-2 342 -63 315 -89 415 37 8 400kV Hoody Devanahalli Line-1 - - - - 6 -36 9 400kV Hoody Devanahalli Line-2 - - - - 6.1 -37 10 HVDC Talcher Kolar Bipole 1280 - 1540 - 1560 152 Page 152 of 153 Annexure-F
Remedial Actions Furnished by SR-2: The failure of GR-MR changeover of Pole-1 was analyzed, and it was found that the sequence had failed due to a sequence issue command to 20B10-Q2 and the same was rectified. The automatic GR-MR changeover of Pole-2 was successfully executed at 22:10hrs. Remedial Actions Furnished by KPTCL: At Hoody end: The error in mapping of O/V function trip to Trip BO has been rectified and tested the O/V function on 16.01.2021. Now, the O/V trip is initiating master trip relay 86A . Direct trip signal was not configured for DR trigger in Main-1 relay at Devanahally end. The same has been rectified on 16.01.2021.
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